I have done several cars that have not moved in 30 plus years, pull the fuel pump stand, add automatic transmission fluid, remove the center head, spray all the lifters with PB, also use diesel fuel and a brush to clean the valley out and lube the lifters. Make sure the transmission is in neutral. Take the belt off the generator and water pumps. The clutch has been stuck several times on two cars I have done. Pull the distributor, add oil, automatic fluid oil, anything you can remove to lube up, it needs to be done. Put car in gear and rock it back and forth, gentle. Add oil to everything you can think of. You will need to drop the mix of fluids out of pan after you break the engine loose. I have always dropped the oil pan and cleaned the sludge out of pan that is always in it and the oil sludge you washed from valley. See if screen on pump is clean. Sounds like a big job, but goes quick. ( yes pull the starter and make sure it spins on the floor with power, it can be froze ) you will need later to spin after it frees up. Drain the radiator, see if the water pumps are stuck.