Thanks for that Grumpy, I usually chuck a nut on bolts before chopping them and then clean up the ends on the wire brush especially dealing with 39 yr old cast alloys lol
Im a bit light on for bolts in my collection so I will probably just buy a handfull of each UNC from 3/4 inch to 1 1/2 inch and see how I go and as im now waiting on a new spring for the clutch carriage assembly (A week including cup day hols) im going to do it right.
Ive found Plasti bond or Metal mend a nice quick fix for stripped out threads BTW or if you feel really nasty Liquid nails will do the job as well.