I am curious as to why you are doing this? Is there something wrong with your current system? A properly maintained electrical system be it 6v or 12v will work much better as designed than modifying it without first determining what the problem is. I don't much like seeing 12 v conversions on a 6v tractor. I have a 56 sitting in the barn that came equipped with a mag and was converted over to 12v. It still has the 6v genny along with a 12v regulator, 6v coil with the outboard ballast resistor and the original 6v cabling. He has a lot of problems starting it .. hmmm wonder why
If as is my hope this becomes my next Cub - it will be restored back to it's 6v configuration. If I want a 12v Cub I will go buy one that is properly done. Course this is JIMHO and means exactly $0.01 worth of value 
Oh yeah, since it has been sitting for a number of years, the very first thing that I would do is to check each and every connection/ground etc., clean until bright metal shows, repair any worn terminals/terminal connections etc., and apply a coat of di-electric grease to each contact point. It could be as simple as that in getting you electrical woes solved. Then you won't have to play with much. If all you end up having to replace is the cut-out or regulator that is a relatively inexpensive fix. Also you may want to take the genny to a good olde tyme auto electric shop - hopefully and AC Delco authorized service centre and they can repair/rebuild your genny for very little. That was the route I took on a number of gennies and a cut-out. Generator and Cut-Out
