Same stroke, long rod is to compensate for short crown to wristpin distance on the IT pistons. Don't think I worked out exact spacing so would probably require cylinder base spacers or machining to get timing and compression right. Long rods were a Banshee aftermarket part; big end was a millimeter or two wider than RD/TZ, so crank would need to be machined or maybe fit an RZ crank. More details never fully worked out. On subject of snowmobile triples in bike frames, https://thekneeslider.com/monotrack-experimental-by-dan-hanebrink/ I remember seeing it at Ontario mid/late 70's. The builder was rather more known for precision swing arm pivot kits for Z1's and RD's. I think except for the tires and clutch belt literally every part on it was carved from billet. Oh and it was an SOB to launch. He was invariably last into turn 1.