Mike, You are going to want to keep your 41 bellhousing, clutch and flywheel. Here's the reason why. The 41-46 trucks have the clutch/ brake pedals in one assembly that bolts directly to the bellhousing plus connection points for the emergency brake. So since you have to use your 41 bell housing you'll need the clutch and flywheel to go with it. You can use your 6v starter even if you change over to 12v it won't hurt anything.

This is a pretty easy swap for your truck. You will need to address the water pump length, but if you check out the links you'll find plenty of info on that.

Good Luck
George