Couple more degrees initial, and I'll bet you could get that motor to run backwards.

Seriously, nosing over early indicates accelerator pump in the carb to me.

Have you checked your timing mark against #1 TDC to make sure the balancer is indexed properly. I agree with lt1. Something sounds odd here.

Also, do you have vacuum advance? If so, did you set the timing with the vacuum line disconnected and plugged?