In need of motor help

[z400rider8787]

so i picked up a 70 GMC LWB and i wanna turn it into a high performance street/mild strip truck. Im gonna be building a 350 and i want around 400-500 hp with decent street manners. what i have so far is an 010 block, an oem forged crank and powdered metal rods. I've already picked out some decent aluminum 200cc heads but i dont really know what type of cam or carb i need. i want a good choppy idle but i dont want to end up over camming it. i was considering roller, if its worth the money. Im gonna run forged pistons in case i wanna spray it some day. but i guess the question im trying to ask is what is a good motor combo to go with? Im relatively new to this and dont know too much