Not a bad price. I found what I believe is an '85 Miyata 310 at a garage sale as well. It has the "Golden Arrow" Shimano derailleurs and shifters as well, which incidentally were the precursors to 105. Look on the back and you'll find the 105 mark. The arrows weren't always painted gold, but the group has come to be known as that. Here's a Schwinn Paramount with a full group. They are competent parts, but are considered middle of the road at best. They do have some interest among collectors, as they were only produced a few years (I believe), but they don't command high prices. I'd stick with them if I were you, if you can bear friction shifting.

I wouldn't dump tons of money into this frame. It is maybe lower mid-range. I find the ride on mine to be a bit dead, as I believe the stays are some variant of high tensile, or many some manganese blend. However, it is a nice, solid frame.

From what I've heard, that's probably a smart move. What's wrong with eBay? Probably the best place to get them for a decent price. Harris Cyclery has some, as do some of the other vintage online retailers, but they tend to be a bit pricey. By the way, I believe the spacing should be 126mm...but I could be wrong.

Derailleurs are much simpler to adjust than bearing assemblies. See Sheldon Brown for help on derailleur adjustment - and pretty much everything else.

Good luck, and where are the pics?

Here's mine (still haven't cleaned it up yet):