I have examined the new B-6's closely and I would also bet that a can from a SK2 600 would fit no problem. The frame looks to be identicle to the old.
Like Paul says, I would bet all the US suppliers have no idea as to what bike you are talking about. You may want to check with some of the European pipe makers as I would bet, someone there would be making a pipe for the new 650 & you could cross reference.