There is only a cuople of reasons the crank won't turn, there's not enough clearnances on either the main bearings or the thrust clearnance or the crank is bent I would start at the front of the block and tighten #1 main cap down at a time and see if the crank will rotate, if not remove it and do #2 and then # 3 and so on. If the crank won't turn with any of the caps tight you may have a main web bore needing align honing or align boring as a result of the block being out of alignment on the mains. Over heating the block can cause this, usually the main caps will not have any inteference fit in the block if that happens Do your main caps fit loosely or do you have to tap them into place or use the bolts to make them fit into the main saddles ? BTW, when it comes to assembling and blueprinting motors everything has to be checked, every machine shop and machinest as well as mechanics makes mistakes, it is the engine assemblers job to find the mistakes and get them corrected before the motor is ran the first time your being tested on this one, you can and will figure it out Let us know what you find and what it takes to fix it