Which transmission are you trying to use? Can you post pictures of the area you're referring to, and the hole for the linkage pivot you're talking about? Cast iron is easy to thread- - - - -just don't try to use a SAE (fine) thread for any particular size bolt. Coarse (UNC) threads work best in cast iron applications.
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!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!