Definitely get the gauge checked. Me, I would stop driving if I got a hot reading... better safe than sorry! So I sorta dislike people who are cavalier about issues like that.
The transmission should be fine; but do keep in mind (if you care) that you will not be able to bump up the power of the engine, ever. That said, that engine and transmission will get you anywhere in the country. Slowly, maybe, but you will make it just fine.
The Green Machine -- 2000 Mountain High Coachworks Summit (Spartan chassis / Cummins ISC)
...and F-Troop: Fearghus, Fiona, and Frankie (Cairn Terriers)