Theres a WHOLE lot more than fork length to worry about. Whats your goal?
It may take a small investment to get the answers you need. Buy a EBR triple and compare it to yours, see if the steering stem is the same. If not, you can still modify the stem to fit the XB frame. Check the off-set of the fork tube holes to yours, see if they are the same as well.
Eric did like to re-use parts and specs between models, maybe you get lucky?