While you check out the prices of everything you may potentially/possibly/might have to pay for- go ahead & order you some
Kroil. You'll need it on that $125 motor...
And that could be all you need to un-"seize" it. Did this $125 motor look seized? Meaning, did it look like it had been indoors, or outdoors?
How did you determine your current engine had a crack in it (& exactly where)? What I'm getting at here is if you can't see the BB on the flywheel, through the hole in the bell housing, how cleaned-up is everything else on the engine? A huge crack would explain some things, for sure, so don't think I'm not believing your observation.
Brad