Which Intake?

Your early heads will flow better. But if the seats are gone, go for the 302's. Get a decent cam, valve springs, and a double true roller timing set. Use late LA viton valve seals. Most 4 barrel intakes will be good including stock 273 and 340/360 intake. I would stay away from "economiser" type intakes as a good 273 will like to rev. Find true TDC. It can be way off by the marks.