No one else has ran into this before? one that rusted out over 60 years of age.

Yes need a 1/4" cup style.... will keep looking.

 

100% positive, I temporarily pushed in a .2500" steel dowel pin.... It stopped the leak, just not how I want it fixed (I am to fussy)

 

Here ya go.
https://www.seastrom-mfg.com/product...tNumber=5791-1

 

Another option.

EIS Inserts : All Metal Expansion Plugs

 

Drill & tap, fuggedabout it. I would do straight threads, 5/16x24, loctite it, and stake a set screw in it.

Bob, the first link would really put some pressure on the hole, it's .020 - .030" larger diameter; the second one is really clever but needs a shoulder.

 

A light touch with a drill bit would put a shoulder in #2.
Anyway, here is the quick and dirty solution - dip a 1/4" steel pop rivet of appropriate length in anaerobic fluid (brown Loctite) and go for it.