What's wrong with my motor?

You know come to think about it I built a 318 years ago that I put in my barracuda. It was a stock bottom end 67 318 that I put 360 heads , stock 2bbl 360 cam new timing chain new gaskets and it was absolutely weak as pond water. I always thought that it was because of the low compression caused by the 360 heads now I'm wondering if I didnt do this too! That engine is long gone but i bet I did this and never knew it!!