QuickFuel 880 Surging/Missing At Wide Open Throttle

Definitely sounds like too much advance. But even at 3400 the vacuum advance could still be pulling advance if it's connected. When checking base or mechanical advance the vacuum needs to be disconnected and plugged off. I'd shoot for about 34 degrees total with mech and initial. Here's a good thread on the vacuum advance. The Allen screw is for setting how much timing the vacuum can adds at part throttle operation. The limiter jimjimjimmy posted makes setting the total without vacuum easier.

how to adjust vacuum advance