617 Alternator Bracket with Buggered threads

[steeleygreg]

The PO had someone replace the alternator. It appears that they buggered up the threads in the lower mounting hole in the bracket, towards the front of the engine. Although there are a number of ways to tackle this problem, I thought I'd get on the forum and look for some collective wisdom!
You can use a standard metric tap to clean the threads up front the front of the engine, but run the risk of mis-aligning the tap. Another approach is to go from the back of the bracket and this has the advantage of keeping the tap in the correct alignment for the thread bore, but using a standard length tap in not long enough to allow you to turn the tap. A 150 mm length tap is available but cost prohibitive and located in England. There is a third alternative and that is to weld a hex bolt to the tap giving it enough length to slide in from the back of the bracket. I wonder if you guy's have any other ideas ?