Heads: Edelbrock E-Tec or similar, in ALUMINUM - weights less and dissipated heat metter so you can run a bit more compression on pump gas. The Vortec style heads in aluminum would be great choise too. WIth alum heads you can do 10:1, with iron heads stay at 9:1.

Higher compression willl give more power and better throttle response.

dist timing: you can have your unist (or buy one done) that will have the total advance in by 2500 or 3000 RPM. 36 degrees is about right to start for TOTAL timing. You DO want a vac advance unit as you'll be on the street.

650 or 750 carb. 750 will give a bit more top end at the expense of bottom end. generally, vac secondaries with auto trans, mech sec with manual.

If you go vortec style heads your choice of intakes is somewhat limited, but will achieve your goal.

as to 300HP at teh rear wheels - pick your transmission carefully - you can lose as little as 25 HP with a manul ot powerglide, to nearly 80 HP with a TH400. 700R4 is a better choice than a TH350, but either on will need some work to hold up to 300HP if you beat on it much.