You need to make a drill jig dowelled to those two fixture jigs, use a drill bushing for tap size drill and another for the tap size---won't need a magnetic base drill, you can do it by hand thru the guide bushings and it should be exact---you just probably won't be able to drill out that relievf space where the knurled part of a standard starter bolt fits---but should be just as good and maybe much better than drilling the starter mount to bolt to that trans adapter