converting SDI to carbs

Yes you could, but what problems are you having? Maybe it's just fixable in the SDI system itself....

But they were doing it with the RT's, you could either use the injector plugs they were using and use your cylinders, or find 600 carb cylinders, shy of that just carbs, and then you would have to run a fuel pressure regulator off the stock pump to not over flow your carbs. The biggest issue is what to do with the computer, either find a carb MPEM, or some of the Cat guys just lay the injectors in the bottom of the bellypan, it has to be done to trick the computer into thinking that everything is alright with the injectors and not put it into limp mode.

But again...what problems are you having? The stock SDI 600 sleds were very reliable, the only issue the RT's had were all because of a poor sealing airbox that allowed belt dust into the bottom end, and because no fuel it built up, killing cranks, so the fix was just to run pods, or some sort of air filter.

My buddy had a RT 1000 that we put a crank it, motor had 2500 miles on it and the crank bearings started going, when we took it apart the isoflex grease in the bearings were black with belt dust and even pulled a piece of belt string out of one of them, so we linked it to the horrible sealing airbox, we talked to a bunch of people who had run pods from day one and didn't have any issues. The problem comes from that the fuel through the bottom ends keep crap from building up, since it offers some sort of a solvent, remove that, nothing gets washed away.

If you're scuffing pistons my bet would be something wrong with the fuel system, not enough fuel pressure? You running EGT's? What does your plug color/piston wash look like?

The only issue is your cylinders have the injector ports that run into the tunnel ports on your SDI motor, you would have to find some way of plugging them.