You sound pretty set on the 4 speed...but..just FYI, I never use 1st gear on my 4 speed. It is the granny/creeper gear you could pull out stumps with or use when hauling a full load of shelled corn to town with.
You may want to stick with the 3 speed. Some of the gears are syncro? 4 speed froma 46 is non syncro and needs to be double clutched.
Just my $.02 after driving a 4 speed...
