Well, the radar stuff has been reworked by phreak to allow multiple types of radars, so it should be integrated into that.
The big problem I see is that it's at the same spot as the communications box and the head ANI, so either they'll block the radar or it'll be hard to read it.
hud_gauges.tbl isn't completely implemented, but it's not all that hard to add new options, I designed it specifically with ease-of-use for programmers in mind. Basically...
1) Add variables for the gauge to the hud_info struct (Usually an int[2]) (hudparse.h)
2) Add the relevant info to the gauges[] array; when referencing a var in the struct, use the HUD_VAR macro. (hudparse.cpp)
3) Load any default strings, not default coordinates which are auto-loaded, in load_hud_defaults() (hudparse.cpp)
4) Add any needed calculations to calculate_gauges, this is called right after everything is loaded. (hudparse.cpp)
5) Change variables in the gauge updating functions to use current_hud->variable_name[0 or 1] rather than (usually) variable_name[gr_screen][0 or 1]