will a 1g tcase fit/work on a 2g?

I'm hoping, but I doubt it.

Yes, As long as the spline count is right, you need the case with more splines, the later tcase from 92+. 100% sure it will work.

... and if the spline count is wrong, just swap the output shaft in the tranny to match the new tcase, if you have the shaft available that is...