Loud pop and sputter on WOT? 68 318 Barracuda

Went for a road trip in my 1968 barracuda, and the car drove well except for situations where I hammer it. It's always had a bit of a hesitation problem that's been easy to get around, and don't know if this is related. When I floor it the engine was run poorly (slight sputter) for a few seconds and then hear a loud "pop" and brief cut in power. I can't tell if the pop is in the exhaust or intake. I'll back it off and it'll run fine again after this. Any idea what the issue is and how to fix it? The engine and drivetrain is completely stock.