There is some thread damage on a spindle hole for the Zerk fitting. The Zerk fitting is the larger 1/8" NPT (I believe that's correct) which uses a 7/16" hex wrench or socket. I'd like to touch up the spindle threads with a tap. Not sure which tap size to order from McMaster-Carr. What is the correct tap for these this Zerk fitting?

Thanks,
-Mike

1955 Chevy 2nd Series 3100 Stepside, 235cid