beefing up my 318???

I was going to say keep the stock intake, they are not bad pieces. My first go quick part would be rear gears. Even a 6 seems fast with 4.10's and 318's like to rev (they are just high revving bored 273's) But an 850 DP Holley on a teen is not the best carb either. Want a 340? Offset grind your 318-3 steel crank to a 3.42 stroke and bore yourself .060 over, there. You got 339..close enough. Just kidding, a .060 over cylinder would be the max overbore of a pre 75 motor. If you learn to wrench, go up to a 1.88 head, like a 308 off a pre magnum 360 van and matching intake.