Yes, it will work. That big of a carb will require smaller jets than what you are running now, as I'm sure you know.
The biggest 'grey area' when installing an older Mikuni carb is which needle you're going to need. Since it came off a completely different application, you will have to swap the needle, and you may have to do a little trial-and-error experimenting to see which needle runs best with your setup.
There's nothing wrong with using a Mikuni carburetor. People are just afraid to tune them, since most everybody on here runs Keihin carbs. It is easier to tune and run a carb with which most of us are familiar. I agree, but a Mikuni will still work fine for you. I run a Mikuni TM carb on my Blaster, and the orange Blaster in my sig pic had a 30mm Mikuni round-slide off of a Polaris 250 2-stroke. It absolutely ripped with that carb, ported top end, and a 3mil Vito's crank.