Swapping from iron to aluminum heads

100% right , would never put any new heads on without some porting , though a little less than 100 hp is nothing to sneeze at (without porting ) , I'm at 398 now anything close to getting up to 460 - 470 hp is good in my books . Where else can I pick up 80+ hp , plus the weight reduction ?

Less than 100HP is a small power gain per dollar spent. That's what I was referring to. With a good port job, that's a whole nuther ball game.