700sx pistons will work too.A member on here used them in a big bore project years ago.I am in the middle of doing one of these.They have a 20mm pin,ring end gap pins are in the right location,but need the reed valve cutaway machined into them which is no problem.The skirts need a bit removed as they come vey close to crank at BDC.Just need pin adapters for these.
I have a 750 that uses DT mx trimoto 175 pistons as well,wiseco piston 471mo6800 which aren't available any longer.You can still get 67.5mm though.they have 16mm pin.The crown is twice as high as a stock piston and must get heads machined.Hauck has 800 pistons now and I may shut project down.
Remember when you overbore large amount,you must redo ports as the ports will all become lower in cylinder once bored out do to upward angle of ports.Lots of time involved and money.