Garth - this is a great topic. One of the cool things about vintage bikes is that you can mix and match all the parts to suit your personal needs and preferences. I remember the cog boards and bins of spare parts at Cupertino Bike Shop and a pilgrimage there to replace an 18 tooth Regina B cog was great fun. However, installing a new cog on that Regina freewheel was truly a "voyage of discovery".... which is why I don't run Reginas any more...
And that brings me to the topic at hand. Modern bikes with their dedicated "systems" don't allow you to mix and match components. You have a choice of BEEF or CHICKEN (Campy or Shimano) plus TOFU (SRAM) and as a result the fun is lost, and all bikes seem pretty much the same. Matter of fact the "generic vintage bike" with all campy 52/42, Regina ORO, Cinelli bars, Martano rims, etc does not interest me very much. What IS interesting is to pick the selection of components that meet your needs exactly, whether it's low gears for hills, or rack mounts for load carrying, whatever. Over time I've arrived at a mix of components that will probably cause me to be banished from the list, but work really well together and provide a pleasant, safe and sustainable riding experience (meaning spare parts are available).
The bikes I most enjoy riding are equipped with Phil Wood hubs and bottom bracket, TA cranks (old style or the excellent modern Carmina) geared 48-34, Shimano freewheel (either Dura Ace or the current chinese el cheepo which works well), Mafac centerpull brakes or the Paul Neo-Racer (really good luck with this one), Campagnolo derailleurs of various types but always the classic Record front, Suntour Power Ratchet shifters (get 'em from Rivendell) and Nitto handlebars.
The result is a bike that works well and is truly a reflection of the owner's individual tastes and preferences.
Bainbridge Island, WA