I'm a little late but what a nightmare, smaller bore, imagine the port work to a thick iron sleeve, what about cooling through all the iron to cooling jacket, and headwork. Flip side short stroke means different crank and now you have all the open area in bottom from smaller crank throw, and pipes are designed for displacement (volume), rpm, and if you found someplace to fabricate the parts..... What would it cost for HPR to build and test 1 pipe. I won't say impossible but improbable just from the $ point. Just my opinion. I would read the story if you do try it though.