i have some 86 lg4 heads , that i believe are the 416 castings, my question is this. What kinda power do you thinki would pick up on when i port these , i have a mild crane cam its a 204/214 duration 423/446 lift. I have headers, cat back, i've got slp runners in the mail, gonna port my intake, ported plenum, free mods, air foil. and im gonna install some roller rockers, im really shooting for 300 hp with my 305. Do you think i can hit it?

 

300 hp is not a problem.

Standard Abrasives flow benched their 305 heads and gained about 20 hp from their porting and polishing, which didn't include any extensive bowl blending or intake valve enlargement.

With the bowl blending and 1.94 intake valves they should be worth around 30 hp. Your cam will be worth at least that much, as well.