A developed version of the pure jet XC-123A could be interesting, particularly if combined with the later fuselage with sponsons for the main landing gear. Perhaps an uprated version using B-52 engine nacelles instead of the B-47 inboard nacelles used on the one aircraft actually built?
For that matter, the sole C-123T prototype was built with T56s and required a redesigned, wet, wing. Replace the R2800s with PW150s or so (basically the same change from Cl-215 to CL415) would work better as you wouldn't need to change the wing and could still use the fuel tanks at the back of the nacelles.
The In Action book shows a variety of users and marking & camouflage schemes.