Just measured mine and it's at 74.2mm (hard to get a good measurement from a cylinder that had a seized piston)...can't find piston anywhere.
No idea how to accurately measure stroke while crank is inside case, but there is a spacer under cylinder.
Cylinder is engraved with LRD, definitely ported, no measurements engraved anywhere, only serial numbers and re-sleeved noted under intake.
Bonus...just realized the head has been O-ringed LOL