Help on 408 build
If the piston is a true zero deck flat top you are easily 13 to 1 compression. You really have 2 problems. You initially said it lacked power. I would be that your heads are choking that thing really bad unless they are pro ported to death with really big valves. Even then it would still hold it back. I totally agree with PRH, you should really do your homework before spends money on a band aid fix. The 230 psi cranking compression confirms the 13 to 1 compression. Changing the camshaft will help with low speed part throttle ping but will actually hurt more at high RPM full throttle. If I were you I would swap the heads to a Edelbrock Performer RPM. The big chamber version. It will probably lower the compression by half a point (do some research on this) and couple it with a little thicker head gasket and you will be near 12 to 1. The aluminum will help soak up the heat energy and it would be equivalent to 11 to 1 with the iron head. The chamber is really good on the edelbrock and will help with quench and hot spots further helping with detonation. You could go further with one of the CNC options from indy or Hughes and have a bigger chamber yet and a huge improvement in performance. Then you run a touch less timing and a less aggressive timing curve to run pump premium.