I don't mean any disrespect, I realize the OP is from Holland so maybe it's a translation thing, but I really don't understand the question. If you grind both the bed and carriage, no more what????
What will be the result?
Well, for starters, unless it's a box way machine it's gonna be tough to grind it such that you have even bearing on all surfaces. Even then, the gib will need to be fitted, tough to do with grinding, but possible I guess.
I think most important will be the lube system. Pressure fed lube, hydrostatic???The surfaces will have 100% contact so they will want to wring out the oil film and stick together. Your lube system will need to be designed to overcome that.
I know some machine makers have tried this sort of arrangement, I'm no expert on the results or exactly what you need to make it work.