Two things to remember--dont force it too hard to turn,or you can crack a ring or do more damage ,let it soak up good for as long as it takes..
Turning the engine over by the balancer bolt often snaps the bolt off in the crank--we had better luck freeing up stuck engines at the junkyard by using a large screwdriver or pry bar on the flywheel teeth ,you get more leverage with the large diameter wheel...sometimes turning it "backwards" works better because any crud trapped between the pistons and heads can stop it from wanting to turn in the normal direction of rotation..once you get it to move backwards you can add more penetrant and keep rocking it..if it seems to turn free ,then jam up,a valve is probably rusted in the guide,and forcing it will either bend a pushrod, or worse...
We had a few old Packards that were seized and the boss wanted us to get them running again,they ran when they were towed in ,but they sat at least a decade,and the engines were bound up good..we soaked them with Marvel Mystery Oil in the spark plug holes,and when that failed,the boss decided to hook up the heater hoses from our torch truck to the Packard's engine and he let it run a good half hour--we saw the temp gauge on its dash actually went up to the center,and we tried turning it with a pry bar on the flywheel and it broke free and spun over,and after we made a few full revolutions and felt nothing was binding,we were able to get it started with the battery by jumping it with the torch truck...and it ran great after awhile..
I know a guy who seized a straight six in a 70 Nova one night--drove it home with no coolant after a minor collision with a tree in a friends yard leaving a party,because he had a few beers in him,and didn't want to get caught!...next day it refused to turn with the starter--he said the exhaust manifold was orange when he got home 8 miles away,and to shut the car off,he had to take the air cleaner off (got his hands singed good doing it too)--and he "smothered" it with a rag!..
He said it kept running and dieseling,even with the key off!.

....we all figured he cooked it so bad it was junk--but he got it to turn over by putting a hydraulic bottle jack against the flywheel teeth,and jacked up on it,until it moved!..got it to to make a few full turns,and it did finally start,but it never had good oil pressure after that,and smoked some after he got it going again..he drove it all winter though,just kept adding oil every 300 miles or so...shows how tough an old chevy six can be!..
