Two things I could think of, first, with 2 plugs out, it doesn’t spin fast enough for a comp test, the starter is weak. Run a check on starter draw. The second is drag. Did the pistons/cylinder get checked for clearance, along with the rings before assembly?

 

Lift the rear wheels and see if you can turn the rear wheel with the trans in 3rd or 4th gear. If not. bore scope the cylinders and see if anything appears out of order. And then amp draw on the starter as mentioned above.

Paul

 

yes did they clearance the pistons? this isnt your problem but CP pistons require .003" clearance the jugs come with .0025"