Is my engine dead?

I had very simular problems with my Dart 318 and it was indeed the timing chain. The factory timing gears were aluminum with a hard plastic coating on the gear tips and over time the plastic breaks up and causes the chain to slip.
I pulled the heads to check for valve/piston damage and there were some very small indentations in the top of a couple of pistons but pulling all the valves and checking them showed nothing bent.
If you have the same issue with the timing gears and the plastic coating is breaking up them pull the oil pan to make sure you get all the bits of plastic out.

Hope this helps.