Check My Cam Degreeing
OP, what model of KB piston do you have? Something is missing from your static CR computation. Is this an LA block?
Any way that you had the crank sprocket at the -4 position, and moving it to the +4 position changed the timing by 8-10 degrees. Something like this might be going on. Sometimes the little stamped geometric shapes that designate the timing keyways are hard to read.