The M-700 has different dimensions than later cab designs, I I would think not. The older style 743 door seems to fit though. As for a heater it depends on your engine. Water cooled ones are easy- you just add another bypass and a heater core. along with some kind of control valve. Should be easy to find in a junkyard or off a handy junk car. If you still have the air cooled Wisconsin your job involves making cowling to direct engine heat to the cab. Having a tight exhaust system and air outlets is critical to keep your enclosed cab from becoming a gas chamber.