66 Dart

First time posting. So I recently purchased a 66 Dodge Dart with the 904 auto trans (I believe) and the 225 "Charger" slant 6. The only guess on mileage is around 26,000(long story lol). Anyways best guess on last it was turned over or moved is 75' possibly. So I believe the motor is locked up.

Anyone have any good tips on breaking it free so I can start working it? I found a bolt to go into the double pulley/crank shaft, the bolt keeps going thru thick washer and doesn't stop turning no matter how much force I've used (obviously a lot since I'm going thru washers) and it hasn't budged yet. I have this far ran a funnel into the spark plug holes and poured marvel mystery oil in, also sprayed an entire can of liquid wrench in, and I've been leaving the spark plugs out.

Attached several pictures for starting the resto.

Thanks for the help! Mopar or No Car!