I do know the Vanguard 810 rods are forged, might be a nice addition. As far as any improvements/differences in the block and sump, I have no idea, but is certainly worth investigating.The heads are interchangeable although the are now a spread valve (rockers are at an angle to each other) and the head gaskets are fire ringed. I've been using the gaskets foe 2 years now. They are the new bigger valves (not quite as big as the OHV single) and more of a square port on the intake. The pistons appear to be severely dished and the rods look more like the old 44 rods (but if forged most likely stronger than the new 49 rods). Just wondering if the added expense would be worth it.