You're in Tuscon? There is a "regional" subforum. Perhaps you could meet someone local.
Southwest - Bike Forums

As mentioned above, there is no one answer. Some parts will be interchangeable, some aren't.

Browse this page a bit:
https://en.wikibooks.org/wiki/Bicycl...ing_Dimensions

What you'll see is that to a large extent, Shimano and Campy don't play nice, but there are a few places that they do.

With Shimano, as cassettes were made wider from 7 speed to 11 speed, the spacing between sprockets was made narrower. So, a 9 speed indexed shifter won't work well with 8 speed, etc.

Derailleurs, however, were quite similar between 7 speed and 10 speed, with a few exceptions.

Going vintage, there is much more flexibility with friction shifters than indexed shifters.

I've had issues with vintage 9 speed Ultegra/Dura Ace shifters, and would probably choose something newer over the old ones.

Anyway, as a few people mentioned above, if you want some specific answers, post some specifics, and an inventory of parts, and people here will give you some direction as to what they might do if they were in your shoes.

Even if you had the BEST mechanic to consult for 15 minutes, their answers are limited to a single point of view, and may not give the best answer for everyone.