These are soon to come out from infinty and would make awesome Vespid for Tau. they just need a little work on the arms to make them hold vespid uber shotguns. I especially like the wings and the heads seem quite simialr to the orignal vespid concept sketches.
Size wise I think the are bigger than normal infantry. Maybe orge or troll sized? Even so I'd still convert the hell out of these, even just to use the wings