oh i does like a nice carbide drill... though they arent quite as impressive as watching a T-drill take out a 50mm hole at 100mm deep in a matter of seconds.
idea with the piston...looks like theres at least a bit of meat around the bosses so you could run an endmill through, putting two flats on the side of the piston.... though looking at the clip grooves...maybe not. (on a 48 at least)
make a split bush clamp so you can ensure concentricity, and you can bore out the back of the skirt a bit, until you meet the bosses (wife...shes a stunner!)