Your best bet is to see what damper you have, 2 o'clock, 2:30 o'clock or noon and go from there. You can make a timing tape
and transfer the marks onto the damper, then use a simple pointer to indicate zero. The timing will then be read from the damper instead of the tiny tabs that don't have enough range to show you total timing and vacuum advance.
If it's a 2:00 damper, that's what most all the aftermarket timing tabs are made for. Buy one and bolt it on. If it's a noon damper, the timing tabs are usually all tack welded to the timing cover. The 2:30 damper can be found w/either tacked or bolted on tabs IIRC.