Mine also has the grease nipple fitted, twice a year I give it about 10 pumps of JCB high pressure waterproof blue grease. It runs as quiet as a whisper at all speeds and loads even down to 2000rpm
The hole in the bell housing is about 1-11/4" dia. This is not critical.
To get a datum measure the centre of the compensator at the top through the steering rack cut out and transfer the measurement to the bottom.
Hope that helps.