Timing help ! Sorry

What are you using for a timing light? If it's a "dial up" light go find a plain ol' timing light, no advance dial.

What kind of ignition system? MSD EG is known for problems with timing lights

And then there's rotor phasing.......................................

It also "could be" that you have some issue IE broken plug, bad plug wire, poor wire terminal connection, CROSSED WIRES, and one of these issues might be causing CROSS FIRING that is also mis-triggering the lamp

WHAT I WOULD DO

Get back down to basics

Get a piston stop and confirm TDC is actually TDC

Pull ALL plugs and wires and inspect or replace the plugs. Also inspect plugs for firing condition, IE "read" them

"Ohm" the plug wires and inspect end terminals

If this is an MSD as mentioned above, get a non-delay timing light, and consider (if you have/ can) temporarily replacing MSD with Mopar or HEI module