HELP! transmission case repair?

No welding. See, what nobody is considering (except ME) is that that's an INLET hole. It has to stay CLEAN. And welding will fry that gasket next to it. Just do like I said and cut it off and re-tap it and install the original fitting, or go look at Lowe's broad selection of brass fittings that could be used to extend it out from the case. This isn't really a big deal to fix. Worst case scenario, you make mess of the hole and have to use JB weld to seal it up around the new fitting. NUMBER ONE is to cram something in there FIRST that you can pull back out when you're done.