Why are 318's low HP and torque?

Hmmm. Okay. Well I have headers already so at least that'll help a lil bit. I just got my oil pan and I'm going to put it on tonight. Going to drop it in soon! Does anyone know if I will have issues putting the engine and trans in with the headman headers on the block?

Also no one confirmed or denied weather or noth my engine already has 302 heads? My engine is from the 80's