1983 is definitely aluminum case. Shoot an email to Roger Brown at California Motorsports/CMS. He's seen a ton of these transmissions and also does repairs to the case. So I bet he's got his own fix for this location. The more common issues he sees at the clutch release fork location is on the G50 trans where the mounting bosses crack off
https://californiamotorsports.net/collections/porsche-g50-transmission/products/cms-g50-993-gt3-clutch-fork-pivot-shaft-boss-repair
He used to weld machined aluminum blocks onto the bellhousing. Apparently he's since developed a more elegant solution above where he screws the pivot blocks into the trans.
He fixed up my differential housing with steel bearing bore sleeves and also welded a crack that he found near the speedometer sending unit recess. He also discovered the threads were messed up in one of the detent holes and installed a helicoil