If it's the 98-99 KB (aka KB Ver.1), I'd take KB n Darnell.
Yeah, Dusty might be stronger than KB, but KB could play D back then when he applied himself, and I don't think Dusty could completely dominate the boards in a 2-on-2 game (especially taking into consideration how good Darnell is on the boards). And Darnell would shut down Willie.
And when you put KB n Darnell together, they understand each other and have great chemistry, which would go a long way towards victory. Your talking about one of the great import duo's in NBL history.
I can't see Dusty n Willie guarding those two in a pick n roll (with Darnell setting the pick and rolling to the basketball - he would kill Willie in the post), or a pick n pop situation (with KB setting the pick, then popping for that unstoppable jumper).
If you played possession (keep the ball after a score), then I'd take KB n Darnell by about 8-10 points.