[Raptor]

If you are just having it machined, specify to the shop how far over you want the bore, and how tight you want the piston wall clearance (different based on piston manuf) They will have the rest of the specs they need to machine it. As far as building the motor loose, depends on what you want to do with it. All out drag, sure build it looser, DD you don't want loose, everything wears a lot faster and is much louder (piston slap etc) Your question of how loose doesn't work, depends on what your referring too, bearing clearances, piston clearances, ring gap etc.