You should not need to grind the block. If the block was the problem the starter would not work no matter what bell housing is used. Simple concept here. The flywheel is fixed off the crankshaft. The bell locates the starter. This is the same with any bell. If your starter is not fitting the block is not the problem. I have heard of the starters not fitting but that was the wiring block on the starter. Lots of minis you just removed the block. The metal dust shield still should be used. I have the kit behind my Hemi. My bets are this. Are the dowels in place? Was the bell housing dialed in properly.