Not identical the bolt patterns for mounts are close (Greyhound 63mm x 104mm) Predator 61.5mm x 102mmYes, the 99cc Predator has the same weight and dimentions as the discontinued blue 79cc engine.
I don't know if the waterpump has a standard pto shaft or not. Sonme pump engimes have a tapered shaft.
Maybe someone else here knows about the pto shaft. That's a flathead engine, nice and compact.