The T-37 is just about gone from USAF service...replaced by the T-6 Texan II. I enjoyed all the time I logged in the jet (1400 hrs) and only wish the engines and avionics had been updated in the 80's like what was proposed. It was a good, solid flying jet trainer and served us well for the past 55 years. It is a shame there aren't more available on the civilian market now, but it would be ridiculously expensive to operate. Full fuel is 309 gals and we would burn nearly all of that for a 1.3-1.5 hour training sortie. It would certainly be a neat project to re-engine (Williams FJ-44s?), remove the ejection seats, and install a glass cockpit of some sort (G1000). I think you would have a nice little private jet in the class of single engine turbos, but with fewer seats.

TFF - we stopped teaching intentional, inverted spins years and years ago. I did have some friends who ended up in the inverted position because of student errors though. You actually had to push forward on the stick to slow the spin before doing a rapid pull back to break the stall. One guy had a dual engine flameout after going inverted - that had to be exciting!

As for making it into a wave soarer...I'm not so sure about that even with 12' of extra wing. Those engines are HEAVY and the wing is FAT and SHORT...not a good combo for a sailplane. With a strong enough wave it might be possible though...

Beau