There must be something caused the clearance to change. When you pulled the seal out, did you need to loosen the other main bearings? That crankshaft should turn with hands on the flywheel, no need to use a pry bar. Not a real close fit on these old engines. I would pull the pan and look to make certain nothing is locking the crankshaft then I would remove the new seal( I know backward motion) and replace the main bearing cap in place. As you torque it try turning the assembly. You will know when it gets tight,Find out why. If it is free without the seal, then try a different rope seal. Try to lube it between the crank and seal before you put on the main bearing cap. Then you get to do the process of torque all over again. If it will turn, then put the pan on and fill with oil. It should work.
