Bottom line is that you don't know the cam specs. Here is what I would do. Pull the heads off the motor, see exactly what pistons you have, CC the chambers on the heads & see if they been machined down. Pull the cam and break it across a metal workbench if you have one, that will let off some of the fustration to this point. Post your findings on here as to what you find out on the heads and pistons and let someone on here suggest a cam for you. If your lucky and your pistons are ok with CR you may be able to just reassemble with a more correct cam for what you have.