A904: 1-2 shift happens early despite governor weight- any way to adjust this?

The rod from the carb should have an adjustment, if not
try to locate one or fabricate out of treaded rod with a turnbuckle for adjustment. From my experience the lenght is a
pretty fine adjustment, too long and the throttle may not be 100% back too short give early shifts. This setup is best taken complete with springs from an unmolested
donor car.