[tbirdtbird]

The hole in the block needs work as everyone has stated. Best to remove head and do it right. It will have to be drilled out. Leave head in place, use appropriate sized drill, shim the outside to just barely fit the hole in the head, then drill thus using head as an alignment jig.

Two choices remain:
1. Helicoil (the kit has its own special drill and tap)
2. Brattons and prolly others have studs that are 1/2-13 on bottom and regular 7/16 stud size up the shaft and top. Brattons # 8170, 8201, 8211 depending on the length you need.

Tap carefully, going forward and backward often to break the chips so you don't lock the tap in and break it. lots of lube, too