Using my 4th axis on my CNC mill the other day, I noticed that it's axis is not quite parallel to it's mounting face

Slipping feeler gauges under the base at various points showed that it was far from flat, so somehow it needs re-working to get the base flat and in one axis parallel to the axis of the rotary part.
I'm sure that the proper way is to scrape it flat and parallel, but it's a huge lump with all sorts of bits sticking out making this approach none too easy.
So in the MadModder tradition I'm trying to think 'outside the box'. Were I to make a base on which to stand it, with three 'levelling screws' then I'm sure that I could fairly easily achieve an acceptable degree of accuracy. BUT the three screws would not stand up to the pressure of use and undoubtedly sink into their beds under load.
So supposing I made up the base and levelling screws, achieved the desired position, then removed it and spread Titanium Putty on the base, and allowed it to sink down to the screws and hence back to level - would that work? I've heard of similar ways of aligning lathe cross slides and bringing them back up to height after a re-grind using Mogalice. After all the 4th axis would still be held down as always to the mill table, so there is no issue with bond strength only compressive forces, and the stuff claims 105 kPa
Or am I mad to consider this approach?