Jetting would definately need to be done. I was thinking of getting a 36mm since everyone on this board has done or is thinking of having their 33mm bored by either Fredette or RB to 36mm.
I put a 35mm KDX 200 carb on my 220 with mixed results. It made the 220 run almost like a 125 with very little bottom end and more top end than the 220 with the stock 33mm carb. It also took me a while to get the jetting dialed in to where it would run cleanly. But still the power was not very good in my opinion. I mush prefer the stock 33mm carb on my 220, but I can see how the RB carb can work great because of the divider.
"Installing a 1988 or newer 35mm carburetor from a KDX200 or boring the stock 33mm carburetor to 36mm will increase mid range to top end power, with only the slightest loss of bottom end power/ throttle response. "
In other word, 'YES.'
**edit**
Not to imply that large body PWKs will not work on the kdx.