Ahhhhh panic!!!

I thought things were going too well... I don't know how I've missed this but the 45 series rexroth extrusion has 10mm diameter holes for M12 screws on the ends. For some unknown reason I've designed my aluminium gantry sides for M6!!! I've seen you can get an M8 "cutting bush" which reduces the bore. Would my best option be to use these and get the side plates drilled out to M8?

=(