Ive tried to design most of the precision critical components with oval holes and left provisions for shims here and there.

Here's a picture of the new "PFC" to explain the "apart bit."
Click image for larger version.  Name: z meas.JPG  Views: 437  Size: 141.5 KB  ID: 10169
Tho I just realized that the number "75" should be actually 100. So many errors. Embarrassing....

So I gather that would be fine?

For bearing spacing on X and Y I do agree, tried to save some cash there but I'll increase it from 150 to 250.

Or would it be any good if I leave the bottom bearings on the gantry with 150 (or 200) spacing and do the top one say 300? (just to get the cutting area that little bit bigger?