hey i have a 77 chevy longbed witha spartan 350 crate engine its 4 bolt maine and it has a edelbrock 600cfm carb n i was wondering how much hp/torque will ported heads give me around? and how much do you think i have right now with all the smog on ... i bought the truck with the motor in and im clueless about the specs, also wats the hardest part of replacing the heads ?