Pat indicated he had a bunch of guys buying the EXC wheel for their 640 Adventures and none of those guys are having problems. Also, I had the gap you have now they I understand the problem fully. After 100 mi no gap. It fit really damn tight too. Now, no problem. I also used some alcohol upon assembly to lube things up a little hoping they'd slide together easier.
I sold my stock rear wheel, sorry I don't have any part numbers. The bike is an '05 525 EXC.