Low compression

[otis71]

I have a 56 FLH and the rear cylinder had much lower compression (125 psi F-90 psi R). I bored both cylinders and installed new low compression pistons. I fluid tested both heads by pouring gas into the ports and combustion chamber, separately of course. The rear leaked a little through the exhaust so I reseated the valves. Now both heads leak absolutely no fluid in either direction. I planed the gasket surface on the rear head and carefully checked the gasket for leaks. With this done the front stayed at 125 and the rear came up slightly to 100 psi. Still low the only thing else I could think of is a shot cam. Both exhaust lobes measure within a few thousands as well as both intake lobes. Is there anything else I could be missing? I’ve been told run it and let the rings seat but with all things the same both should be closer, not to mention in its current state it’s almost impossible to start cold.