Setting timing

A few suggestions that might help. Make sure the piston is at tdc when timing mark is at 0 deg.

Make sure vacuum advance hose is unplugged
set at 36-40 deg at 3000, rev engine to make sure mechanical advance is all in.

Reconnect vacuum advance to ported vacuum. That should take care of timing adjustment.

If problem persists check cam timing:

Remove rocker cover, turn engine be hand, watch #1 cyl. exhaust rocker closing, turn until intake starts opening,continue to 0deg./tdc, valves should be lifted the same amount off seats. Easy check is with a breaker bar rock engine back and forth between +20 and -20 deg., rocker arms should move the same amount, one closing,one opening.

If stock exhaust and OEM headpipe/s:

Check for obstruction caused by inner "ply" caving in and plugging pipe. I found a few of these back in the 60's