Having Starter issues

[apence021]

So I recently went to a 350 and a t5 but I reused the original 6cyl bellhousin so I can use the z bar and I went to use the 3 bolt starter that was working on the 6 and it grinds and freezes up the flywheel is 168 tooth and the starter is also to my best of knowledge. Did I **** up by using the old bellhousin? It bolted straight up so I didn't give it a second thought and nothing scraps or rubs I can spin motor by hand. Should I see if I can use a 350 starter if I can get it to clear the hole on the bellhousin worst case I cut it open a lil bit more but I'm just trying to figure out if this is a common issue or if other people experienced this. I have a engine mount small flywheel starter so I can mock everything up but I would like every one's opinion before I go and buy another starter because they don't do returns on anything electrical at the parts store here