EGR Tube Thread Size on 258

[DadsCJ7]

I just bought a used exhaust manifold for my 77 CJ7 . I am converting to the 80's style. The manifold that I bought had VERY little rust, but the EGR tube was broken off and the fitting for it was very stuck. In the process of cutting the fitting out of the hole, I bugared the threads in the manifold. Can anyone tell me what size threads these are? They look too fine to be an NPT thread.
I want to run a tap thru the hole and clean them up.
Please advise.
Thanks,
Brad