Fordfarmer is correct, follow his advice and that's about the best you can do.
That said, Ford's solution to the problem for later models was a bracket around the handle that allowed the operator to pause mid-travel. It included an adjustable bolt for fine tuning. Something to look into.
Look in the parts book at a 4610 or even a 4630, and you should be able to at least see what it looks like. I'd normally provide a link, but the NH parts site currently has me a little irritated.