Im currently running a 500 cfm edelbrock carb. But im wondering if its too small? Here are my engine specs.what do you guys recommend?

390 bored over 30
Comp cams 270 magnum cam
Msd ready to run dizzy
Hooker headers
performer intake
Slightly ported c8AE-H heads
10.4 compression
3:50 posi
stock c6 and convertor

This is my weekend only hot rod truck so fuel economy is not a concern

 

Edelbrock Thunder Series 800cfm, with the AVS or air valve secondary's the engine only gets as much air it needs despite your best efforts to push the gas pedal through the firewall

 

It really depends on what rpm you want to run. if you stay below 5000rpm, then the 500 should be fine. The smaller carb will usually have better throttle response and mpg. if it is running good, I would leave it alone.
As a comparison, my old 77 had a 460 with a Performer intake, CompCams 268h cam and headers and ran fine with a 600 carb. It ran about the same with a 750, so I kept the 600 on it when I sold it.