The Minne horizontial has a 50mm square pattern with a 70mm diag. Its the same as a YD.
You will have to build it on a YD. You can get wrist pins/pistons in both 10&12mm for the Minnie. With the newer
bigger engines coming out Im seeing YDs drop a bit in price. My gut is aYD/Minnie will easily out do all but the stoutest modded CGs. And is cost effective too. Buy a engine only YD, a horizontal cylinder kit, a G2 reed set,
and a carb and you are basically there. Throw in a jog pipe and build away. I will do this at some point in the future.