There are a couple things you can do to update your '47. But ... really it is simply just good maintenance. The following links are a couple projects I did to improve/replace degraded/missing parts.
1. How To Upgrade A Cub Fuel System
2. How To Build A Replacement Battery Cable
Converting to 12 volt is a waste of time unless of course you were missing the generator, regulator etc., and it would be cheaper to get an alternator. However if you 6v is working - clean it up. Start with the battery connections - make sure all connections are clean and bright then do the same with the grounds etc., they need to be clean and bright metal .. as well as all terminal connections. Also check all of your cables for corrosion or breaks in the insulation which could cause internal corrosion and lead to degradation of the circuit. If the cabling is degraded, replace them. A properly maintained 6v system will provide all the starting insurance that you need. I use my Cub all the time and it is 6v and starts nicely even in -30C and below weather. Sometimes my 12v stuff won't start ... course then it boils down to CCA of the battery.
Same with the fuel system. There are a few things you can do to the fuel system to make it work better but then again most of it really is maintenance. Clean your tank, the fuels sediment bowl, fuel line and carb is clean with no dirt, crud or other foreign objects in it. Ensure that the screens are present and clean. Bring it back to IH Specs and if you want to make it easier add a ball valve instead of the T-shaped shut-off valve.
A good tuneup as well as checking the valve lash will do wonders and of course SeaFoam in the gas and oil will be a good idea.