If you search for differences between 64X (=65R) and 62T you would probably have come up with the answer your looking for. As BruceSki said, has 2 pulse lines for dual 44mm carbies. 62T runs dual 38's.
Again as BruceSki pointed out different electrics. The 760 has the rear cylinder ignition retarded. It also runs 5psi less compression on the rear cylinder. This was done by Yamaha to prevent crankshaft twisting. The crankshaft in this 90hp motor first appeared in a 50hp 650.
Although the cylinder is stamped 62T, the same stamp as the 701 cylinder, the 760 cylinder has extra gusseting.
If a 760 short block were to be used in a superjet, 61X or 62T flywheel and stator can be used as long as they are matched. They can't be mixed as the 62T stator is bigger. Either 61X or 62T CDI can be used. A 62T CDI can be used with a 61X stator if a male to make jumper is made up for the white/red wire. A superjet doesn't load the engine like a couch, hence less chance of twisting the crank.
Again on a lighter craft, don't need to run lower comp in rear cylinder so aftermarket heads with equal size domes can be used.
If it's going into a couch though, better to keep stock head and electrics to keep the reliability that Yamaha designed into this.
