Here is what I have done. I've got this pretty nice Raleigh Super Course frame 54cm, and a Raleigh threaded fork from 64cm frame. I'm strapped for cash, so I decided to hack original headset (threaded) in to threadless type. Here is what I've done: bottom part of headset stays the same, upper head-tube race stays the same, bearings - same, adjustable race (the one with the thread) - thread removed so it slides all the way down past the thread and on to the threadless side of the fork. So basically if there is no stem the fork can easily slide out. Now, the only stem I have is 1.8", so I had to make a shim from an old seat post. I made it the height of the stem, and cut a slit diagonally, so it can be clamped with the stem. So I installed stem with the shim on to the threadless part of the fork. Now the only thing left, is to accurately cut the top of the fork to dsired height, install star nut iside the fork, install washers for correct stem heigt, and install and tighten the stem cap and stem bolt. I have not installed the stem bolt, but i've tightened the stem and fork spins smoothly, but with tiny play at the bearigs. I think that would be corrected when I install the stem tightening bolt and torque everything nicely.
So what do you guys think, am I insane, is it a good idea, any suggestions?

As long as everything's happening below the threaded portion, I think you're fine. However, aesthetically I can't agree with what you're doing, especially on a lovely Super Course with those lugs. Fortunately, you can just swap out the whole arrangement at a later time.

I think you should get the right size fork as soon as possible. That is not an aesthetically pleasing arrangement in my opinion. When you get your new fork, let me know. I currently have a 64cm '78 raleigh Super Course with a bent fork

no reason why it won't work, but you might get better action with an actual Aheadset type headset (1" of course) and a 1" stem will look less clunky (but not much) than the 1-1/8" and shim.Since you have a bit of steerer to play with I'd cut it long and use a stack of spacers, this will help if you make a mistake and need to cut again and also will get the h-bars up to a height more like the quill stem it once had.

The original fork would be hard to find. Maybe I should get a proper threadless headset and use the current saw-off fork? Or maybe 1" carbon fiber from Craigs List? I've seen CF fork $50 and headset $70 (Chris King) a while ago on CL. I could find Aftermarket steel chrome forks, but only threadless type.

VS this:

So do you think it would be OK to have this vintage bike with carbon fork, and threadless stem to have a modern spin on the vintage bike?
Or is it better to have original vintage look with steel fork and quill stem?
I think some time in the future I'll upgrade the wheels and cranks perhaps.
By the way, does any one know how much does this bike weigh all built-up?

These are questions only you can answer...how much $$ and time do you have to play with? If you can wait and keep looking (post a ISO/WTB here for starters) you should be able to find a steel replacement fork with threads (and a better match than that chrome job) and it shouldn't break the bank, you might need a new HS with standard threads, but Tange Levins are only $15-$20.
Plus if you cut it you'll be ruining a Raleigh fork that muccapazza wants to buy off you .
If you can get an Ouzo CF fork for $50, buy it! But really cheepo CF forks are no bargain, they are made so fast'n'dirty that they'll be guaranteed out of alignment (and possibly dangerous). A *good* quality CF fork and Aheadset and stem won't win you lots of style points with us here in C&V, but might be fine for you to actually RIDE, and better than "Drewing" your Super Course, in my book

I have some free time on my hands, but currently not much money. How much do you guys think this frame is worth? Should I invest a lot of money in it, I mean what kind of bikes can I compare this to, like Schwinn Paramount, or Colnago Master perhaps?

If you want a monetary figure, a frame like that in good condition would sell for $100-150 here in the Bay Area and up in Seattle. At the same time, I've seen entire Super Courses sell for slightly higher in the $150-200 range.

Numbers aside, I think the Super Course is a gorgeous frame. Half-chrome fork and stays, nice lugs, a Reynolds 531 main triangle, and that lovely British green make for a solid combination. No, it's not butted, and the rear triangle isn't 531, but it's still a sure keeper.

It really comes down to you, though. I have a Peugeot UO-8 that's probably worth no more than $50 prior to the vintage bubble, but I love it.

Uh, no...it's a Super Course, not a Paramount, not a Colnago.
I haven't owned one since I was a teenager, but I did plenty of mods to mine (including a gloss black paint job...with a BRUSH).
It will ride fine, and I'm sure there's folks here that love them beyond reason, but it's not a thoroughbred. We just don't like seeing any vintage bike with Nervex Pro lugs and 3 tubes of plain-gauge 531 treated *too* badly

Does any one know how much does Super Course weigh compared to say Trek with Reynolds 531 tubbing. Is it more than average 24lbs? It sucks it's not a Paramount, but weight wise is it close?

Unless you're a racer, the weight is just a number folks like to compare. The best metric is how the bike rides--and for everyone it'll be different.

I have called the guy I've got the frame from, and he said it was sitting in the garage it all the stuff (he is a very serious pack rat) for a long time, and there was a fork for this frame, somewhere. He wanted to restore it, but newer had time. He'll look for it and call me back if he finds it. I'm sure have my fingers crossed.

I vote for insane, but if you can make it work, cool.

It's just hard to look at those lugs and that stem at the same time. My brain went ka-dunk.