High-Torque 6 volt starter has been discussed here before. Well, I found a guy in Oregon that can do this. I sent a starter to him and he converted it. And yes, it is high-torque, there is no comparison as to the way it was before. It spins my 216 like it means business.
This gentleman will also put a 6 volt alternator in your generator case and redo some internal work to your voltage regulator so the wiring will be orginial.
I mention this in case someone may be interested. I have no interest in this, I get the same if you have the work done or not, $0.00.
His name is Don Allen and
his web site He makes no mention of the starter on his site. His number is on his site if you want to call.