Guyver... Sounds like a nice rig. As for intakes, the twice barrel will give you all the fuel air mixture that ride can handle. Putting a 4 barrel and different intake on there will give you a few more rpm above five grand...but how often are you planning on running her up there?
If you just MUST make an intake change do it with a throttle body.. It is a far better swap than a 4 barrel.
If it runs nicely, which I think you have indicated, just keep it stock.
Now if you intend to pull the 304 and do some head work and install a real good camshaft with little overlap and high lift, headers and dual exhausts, by all means put the big intake and a nice 400 or LESS cfm carb on there.. BUT just adding the carb will only make some noise as it trys to burn more fuel.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />