still suspect timing...
check and fix ALL vac leaks if not already done
set points - gap and check with dwell meter if possible. MUST be dead on or very very close to dead on.
useing timing light, set timing. verify vac advance is working and hooked to the right port.

THen road test and report...check jetting then.

Make ONE change at a time so you can identify what that change has done! If you change jetting, points and timing and then road test and it is worse. different, etc then youwon't know which of the 3 items fixes it!