Call RMbuilder, you will never call another cam tech line again. Hundreds of us here have used him.

The fuel system might need some upgrading and there will be a limit to how much cam you can use before reversion becomes a problem but that 502 Mag MPI cam is really mild. I bet you could see a 50hp improvement with the right one.

More than the cam being to small it can't pull the prop it still should be able to. Try different styles of props.

Cam is too small and power falls off hard beyond 5000rpms. If anything, I would try a slightly bigger prop.

Also, whats the timing set at???

Just finished a cylinder leakage test, the exhaust valves leak bye 24 percent on number 1&2 cylinder 7&8 are 12 percent. All other are only 6 to 8 percent. Can these heads be the problem?