I would put a Keensert in it. This will give you the original size thread and will not leak. Provided there is enough material to install the Keensert.

__________________
Gary


1973 450SL
1999 Silverado 4X4 Ext Cab
1999 Mercury Sable
1972 450SL Parts car

Previously owned keepers:
1967 MGCGT - 3L-6
1972 Mustang Fastback - 351C

Current Cylinder Index: 37