I'd have a frame builder replace the seat lugs and seat stays with something other than that horrid-looking fastback arrangement.

Wipe the thought of 27" rims from your mind. Sure, you can make them work, but why? I'd go with tubular rims, but I can accept that they aren't for everyone. Something silver that polishes up nice in either case. Campagnolo, Ofmega, Gipiemme or OMAS hubs would look "right" IMO.

If you want a slightly more modern drivetrain, find out first whether the geometry is conducive to working with something beyond the 6 speed it came with. Shadowfax (my '70) really doesn't like the idea of running with more than the 5 she came with. If going to 7 is not a problem, and you want that, Shimano indexed downtube shifters with the appropriate derailleurs and freewheels would be the way to go. I'd lean towards Dura Ace, but even 600 and 105 should look decent and work well. Superbe might be another option to consider. As much as I like Campagnolo, I can't recall seeing or hearing anything to suggest they got this technology down nearly as well as Shimano and Sun Tour. Shame, since this model begs to have Italian bits hung on it...

If you are ok with a friction drivetrain, stick with Campagnolo. My preference would be SR in front, and NR in the rear (I think SR rear derailleurs are butt-ugly in comparison to NR too). I'm fuzzy on this, but I think SR is compatible with a slightly greater range of gearing options, and since I know you ride in Pennsylvania (with our hills), that might push you towards SR. A Record seat post is a bit more of a P.I.T.A. to set up and adjust than the other options, but it gives you complete control over every element of saddle adjustment. Go with whatever suits you there. Levers? If you go aero, get a handlebar with the appropriate grooves.

Looks like a fun build, and it should be gorgeous and a great rider when it is complete.

No go. Get busy.