| If you're after an upright electric, or a laminated (plywood) bass, then sure. EUB would be easier, as custom plywood is virtually non-existent. It you meant a properly carved doublebass... then no, it is highly unlikely that any luthier would waste their time carving a spalted belly. Both acoustically and structurally it would make no sense. Spruce is the standard, has been for centuries, and for important reasons in terms of both structural and acoustical engineering. Spruce moves differently, has radically different stiffness along and across the grain, where a hardwood like this, especially with live rot (that's what spalting is), is almost plastic-like in that these two flexibilities are almost identical. | 
