You need to re-read Magnum Valiant’s post. You align the bell housing with the dowel pins removed then drill the dowel pin holes oversized. The only issue I see is that the bell housing and the drill centerline must not move during the drilling process. If it were me I’d sandwich an oversized steel plate between the bell housing and the block and use a mag drill. The one problem that this creates is that the block and bell housing have oversized dowels and dowel holes so switching transmissions or bell housings becomes a problem in the future. With that said I’d use offset dowels.
