Help! Wiped cam lobes? - Video inside

Backfiring is not going to happen over wiped lobes.

When the cam lobes flatten, the valves have exactly the opposite problem. They don't open enough and stay closed for a longer duration. Backfiring through the carburetor is caused from the ignition firing when the intake valve is open. It could be hung open from a stuck lifter, or it could be doing exactly what it should be doing and the spark could be igniting when it is not supposed to be.

Is it backfiring through the carburetor or exhaust?

If it is coming from the exhaust, you could also have a burnt valve seat.

A leakdown check will tell you if it is valve related.

If you don't want to rent/borrow/buy a leakdown kit, AJ's advice is sound on the ignition end.

The first thing I would check is the ignition timing on a light, followed by a leakdown test.