The pt. No. of your INU is: 452080-05.
The TSO for that unit is TSO-C5C which shows a LTN72 control panel as pt. No. 452090-02
That would suggest the first control panel depicted above, with the Dim selector in the middle, would be suitable. Litton were taken over by Northrop Grumman.
Inertial systems at the time had allowable drift of X number of miles.
Where X = 3+3T and T was the sector time.
For example, an 8-hour flight would mean the maximum allowable drift would be:
3 + (3 x 8) = 27 miles. The systems were quite reliable unless not used for some time, in which case they tended to fail at start up.
I have no idea what the RH represents, There are R and RL models as well.