I'd suggest using a coupling nut, and grind about a 1/2" long shoulder on it to center the hole in the top. Maybe use a flat washer to spread the load out across a wider area. Then you could either weld/braze a couple of wings onto it, or just use a wrench to tighten it.

www.ebay.com/itm/302491604783?

Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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