My first choice would be Amboyna, but it has to have some red in it, not just brown. That's my personal preference, but amboyna in general looks great with ebony.
My second choice would be Tulipwood. It's a lighter colored wood, and that creates contrast with the ebony forearm. Cocobolo is too dark, IMHO, to really stand out. Lacewood would also make good points, I guess, but I'm not too fond of the figuring...too "busy" for my tastes.