Wingman, here's an answer for and really old question! before Novarossi did the long stroke offroad engines they were square 16.45 x 16.45 like the first couple genereations of RB s7 & ws7 those rods were 30mm. those fit directly on the engines if you raise the sleeve .5mm, but you can also do it with an OS or sirio rod.

Kind of late maybe

xe