Not sure a KZ1300 would make a great sidecar engine Kyler. The only thing I can remember is it's liquid cooling would be good. Like the CBX, the six is wide and heavy, and the ZK was designed for touring with a shaft drive. The GPZ1100 would be the better choice.
Basically the rule change will create an 'arms race', costs will go way up, and in the end likely not do anything to create bigger grids. They should have allowed the TZ750 while they were at it. At least that is a period correct engine that was actually used.
"Anyone can build a race car, the trick is to make it fast." - Harvey Postlethwaite