Back from the dead, thinking about this the other day posting here just in case somebody has the same thought, almost works but probably doesn't. 1GR pistons have same 22mm pin, same 94mm bore and are close enough in compression height to work would need some offset crank grinding and decked block (only 1.5mm too low) . The pistons will need to be converted into flat tops on a lathe (easy if you have one) 1gr pistons feature much thinner rings and shorter skits for less friction and most likely a better skit shape, skit coating, less reciprocating mass, inexpensive, etc.
1gr rod ratio 1.68 compression height 32.7mm
3f rod ratio 1.55 piston compression height: 37.5mm
2f crank with 3f rods ratio 1.45 (this is just too low and no good for a long lasting engine)
1gr rod ratio 1.68 compression height 32.7mm
3f rod ratio 1.55 piston compression height: 37.5mm
2f crank with 3f rods ratio 1.45 (this is just too low and no good for a long lasting engine)