My 305 has everything going for it except the heads. I ported them but I'm looking for a set that will increase the air flow better than the small ones I have now. There are so many of them avaliable for the sbc I don't know which one to pick. It's a 1982 model from a GMC truck. With all that I've added I have 303 HP and 313 lbs. at the crank but with better heads I should be able to get another 30 HP out of the 305.