First the felpro 8519 is not .029 thick , it's .039 , but the compression is still 10.0ish in a 440 with a zero deck piston .
Next is shimming the rocker shafts for preload , did you have ave incorrect rocker tip to valve tip geometry ? If you did then that's fine , if you didn't then you should check it as it sounds like you used the shims to make up for milling the heads which is the WRONG use for rocker shaft shims ...
