What camshaft should I use?

I tried to do it while cold and it actually added misfires and it was tapping like a diesel.

The carburetor sounds fine. No popping, but it definitely doesn’t like being loaded up. Even after idling in neutral for a few seconds after it was running much rougher overall.

You can try a compression test. If you have one cylinder that's a "good bit" higher than the rest, that would indicate a closed exhaust valve.