I'd go with the aircleaner, still using the factory aircleaner and snorkel, evrything underbonnet still fairly stock looking.
Also only has a standard single exhaust and no headers won't be helping matters either.
Carby should be heaps big enough, a Barry Grant 625, website says "The Road Demon™ 625 targets mild performance engines from 302 to 400 cid, and rated at 250-350 horsepower."
Given on a 302 with mild cam, be suprised if I was seeing 300hp, especially with stock exhaust & aircleaner.
yoda69