drill and tap for a relatively large bolt (3/8, 7/16), cutoff wheel and smooth off excess bolt , and then drill and tap stock size. Did it once on a rearend yoke on a truck, and got away with it. No problem on a low tension valve cover bolt.
I went this route this morning but went ahead and tapped the new bigger bolt first. 3/8" bolt is jb welded into the new threads, I think it'll hold pretty well for what it needs to do.
