bowtiy

im sure this is a common issue.. and ive searched the site for a bit with not much luck. i just bought a banshee, guy said its a 421cc has a 4 mil hotrods crank, ported cheetah jug w/powervalves 68.5 bore. came with 2 sets domes 18cc and 20cc.. he said its race gas only with the 18's and can run pump gas with the 20's.. currently has 18's installed a cranking compression of an even 150 on both cylinders @2700' elevation.. does this seem low for this motor combo? if so where should it be at? just curious if its getting close to needing freshened or if i'm in the ball park... runs very strong. thanks in advance and sorry if i missed an answer somewhere in the search window..