318 Running Rough / Backfiring

Yup, from scratch, double check/re set the timing. Check under the cap for clean contacts. Good wires!
Run fresh plugs.

Recheck the carb is clean, clear down the barrels. Float properly adjusted for proper fuel level.

Heck full advance with vacuum line off first, then check connected. Make sure the springs/weights/advance plate moves freely and come to a full rest.

These things if dirty, clogged, not fully creek living will cause issues.