roadkill,
As far as I know, there were very little external differences between the DC-9 and the C-9 Nightingale. The SOES (Station Operations & Engineering Squadron) squadron at Cherry Point, NC, had a C-9, and I couldn't see any differences externally between it and the DC-9 (other than the paint job), although I'm sure there are a few. Internally, though, there's a whole slew of differences, especially if the C-9 is set up for medevac use. Are you planning on showing the interior?
I'm not sure about the T-43. The pictures I've seen of one showed it to have a huge nose radome for the radar set used in it. I think it's used to train airborne radar operators, but I don't remember for sure. If you do find the conversion sets, post some pictures of the finished products. We'd all like to see them!