Hi Beau, and welcome. Your brother, on his rare visits, always leaves a big impression here (of course, he could hardly avoid that)... I had an '80 CX500 (D model) for about a decade: excellent bike that always did what was asked of it in exchange for very minimal attention - never got anything as exotic as aftermarket carbs, for sure. There are a set of stock CX500 triple trees and fork legs - maybe a wheel and disc, too - at my shop, any or all of which are available gratis should the need arise. I think Lindy Schramm gave me a CX500C tank, too, though I can't bring it to mind just now.
I'll be interested to hear about the carbs - are you mounting them in the original, short-runner, high rpm CX location, or the long-runner, high-torque GL500 position? My CX had, I thought, pretty decent mid-range, but they say the GL had more, at the expense of some top end.