High RPM Backfire when fully warmed

Hello, I have been having this issue on my magnum engine! When it’s cold it will rev up to 6k-6500 RPM with no issues. But when she’s warmed up really good she will backfire around 5500RPMS and that’s about it. I have a stock Mopar electronic ignition system, a rpm air gap, a Holley 3310 750 with 70 primaries and 76 secondary’s. I have 35 degrees total no VCAN attached. Camshaft is 224@.50 regrind.

I’m thinking when the car warms up my carburetor mixture leans out and is causing this issue at the top end. Does my jet combo sound okay?

Or my ignition system can’t hang?

What do you guys think!