As I now have removed the stock muffler hanger/ brake pivot/passenger peg plate on my 350, I can also remove the steel spacer, and use a shorter 10mm aft bottom engine mount bolt.
As I now am away at work until January, I have plenty of time for online parts shopping......
So what I need to know is what length of M10x1.25 bolt is required when removing the mentioned parts. Or alternatively, what is the outside measurement of the bottom aft engine mounting lugs on a RD350 frame (I will then add approx 10 mm for the nut, in case you wondered)