I used to instal XRay machines, we used M16 chemifix. The ones in the glass ampules with a stud were the best. We used a template, so the positioning was good, but still only within a couple of mm rebar permitting. This did not matter too much as the holes in the machine were 20mm dia.
The thought of trying to get 8 M12 bolts accurate enough for the M12 holes was bothering me. Now I know how stable the lathe is, I think I can just use M8
I was looking at the type with the fixing tool, I have used them before, I always preferred the type with the spring loaded expanding shell. You can always get them back out, and expand a lot which is good for over size/bad holes.
Adrian