one more question

You can change the crank without removing the heads. Had to do this once on a 318 that had a crank that was out of balance and shaking my teeth out... I swapped it without pulling the engine as well. You do need to be mindful that you may end up with a engine that is not well balanced and to resolve that would require pulling the heads so the pistons can be pulled to go with the other rotating assembly for the work.