What is wrong with this combo

So your heads flow 313 at .700 and your cam is netting out somewhere around .650, you aren't using all the head. Secondly as Moper asked what are the mid lift flow numbers. These can be more important than peak flow, W2's are good mid lift flowing heads.

Thirdly you are running a four speed with a very small tire and leaf springs albeit with CalTracs. This can't compare to the ladder bar car.

Fourth the 4 speed is heavy and bulky, how are you shifting it and what RPM, you may be winging it to high or not high enough. Lots of variables.