Is the cam timing the problem, or something else?

My 360 is not performing anywhere near how it should. It has little to no low end power, will not spin the tires, even with 4.10 gears in the rear end, even with the RPM's up, it's still gutless. I have corrected some of the issues with voltage drop to the ignition, which has helped with some of the problems, it does run smoother, but still stinkin' rich, and gutless. I have been reading up on cam timing and degreeing, and have come to the conclusion that the cam is either ground incorrectly, or significantly retarded.

The engine is a 1974 block, stock bottom end and heads and has Melling cam with these specs
Adv exh duration - 298*
Adv int duration - 288*
Exh dur @.050 - 224*
Int dur @.050 - 214*
Int lift - .444
Exh lift - .466
LSA - 112*
Cranking compression is 125 to 135 psi, according to my crappy Chinesium compression tester.

Cam was installed "straight up", with a new double roller chain.

Intake manifold is currently a stock cast iron of unknown origin, (will be swapped for a Weiand Action plus soon), paired with an Edelbrock AVS2 650 CFM carb, ignition is MSD 6 Plus, MSD Blaster coil, and MSD billet distributor. Car has TTi step headers into 2.5 inch exhaust and Flowmaster 40 series mufflers. Trans is a 727 with unknown convertor.

Engine will idle well once warmed up, but even in park, there is poor throttle response, and the exhaust smells very rich, regardless of where the idle mixture screws are set.

Any help, suggestions or ideas are welcome. TIA