bolt in sprag?

Is it possible to drill and tap treads into a stock over running clutch to make it
"bolt on" ?
What are the other considerations I'm over looking or just plain ignorant of ?

thanks.

Yes, the material isn't that hard, I've done it many times. If you're doing it in place you'll need a long tap like a pulley tap.

Is the outer race loose in the case?

Yes is it possible to drill the outer race , that is all the standard replacement bolt in is, a drilled stock unit , it is made to replace 0one that has become loose in the case , it does nothing to stop the over running clutch from failing, if that is your reason for going to a bolt in.