it might physically fit, but the pipe was probably designed to flow the spent gasses from a 750 cc motor, rather than a 600cc motor....there is a definate difference in these two concepts.....sell it on ebay and get the exact application u need
You can probably get away with it. You may just need to open up the ports on the exhaust side a little and then use aftermarket cams to get full advantage of it. Chances are the 750's not going to have that much larger exhaust anyways. I'd just try it.