No sense in trying to fix the crank end unless you can fix the rod/bearing.
For that you would need rod, bearing and new crank pin. You press out the pin with a hydraulic press and press the new pieces back together. You need a good set of V-blocks to set the crank in and a dial indicator to check the crank for runout and radial trueness. You may have to adjust again with the press. The lower end bearing/rod should also should have correct end play.
If you could do the above and acquire the parts needed a good welder could MIG/TIG over the stripped threads and a machine shop could turn the piece smooth then re- thread to accept the clutch, do this before attempting rod R + R (e.g. with crank apart working on stripped half).
This is A LOT OF WORK. Look for a good used crank or complete bottom end instead (new seals too?). Check it for run out (see above), the lower bearing/end play, and the upper rods bearing surface for scoring (better yet check it with a snap guage for wear).
