Even if you get the rod caps and main bearings unbolted, there's still the issue of the timing gears and the plate between the timing cover and the block to deal with. It's a lot simpler to put all that effort into making the pistons move, even if you have to do it with heat, a block of hard wood, and a sledge hammer. I've also seen people use a cutting torch and hack the rods off just above the crankshaft and at the wrist pins to allow the crank to turn a little.
Jerry
