I have a question regarding the choice of a new threaded headset for my bare frame: by my measurements the headtube is 168mm long, the steerer tube (measured from the base of the fat bit at the bottom to the top of the threads) is 205mm long, so does that mean I can fit a headset with a stack height of 37mm or lower?
I was thinking about the Shimano Dura-Ace 7410, would its 37.6mm stack height preclude it? If so, then perhaps someone would be kind enough to suggest something else?
Here's a picture of the frame and fork:

Actually maybe a 40 mm headset will fit too, remember that the lockring is about 5 mm height depending on the brand and headset model and pretty much u need to have at least 2.5 mm of the lockring in the threads too.

Pretty much almost all the good headsets are between 35 and 42 mm stack just in case.

Good luck.

The Shimano HP-6500 also shown on the tech document you referenced should be less expensive and just as good. That Ultegra cartridge bearing headset was a real bargain and very durable. The stack height should be ok.

Actually your fork is perfect for that headset. You need clearance between the top of the fork and the inside top of the locknut, otherwise you won't be able to adjust the headset. Usually manufacturers allow 1mm clearance in their stack height calculation, another .6mm won't be an issue at all. Feel free to use any headset with a published stack height of 39mm or less. If you go taller, you'll have to eliminate a washer.

Many, many thanks for your advice and opinions.

The frame and fork was made by Roy Thame in London during the 70's. There is a partially readable serial on the BB shell but nothing but an oval stamp on the steerer tube. Does anyone have any info. regarding the dating of Roy Thame frames. I also would like to find out what model it is.
I previously created a thread in Vintage bike subforum but that didn't really get me any answers.

You might get a better response about Thame frames on the Classic Rendezvous (Google Group) forum. Several old English framebuilders hang out there.

Many thanks Ex Pres. I'll try that.