I can't get my comment to post at Mary Beard's blog this a.m. (probably our school filters), but the suggestion has been made by 'Ed' (and agreed to by Dr. Beard), that the bust might actually be a head broken from a larger statue. If so -- and I can't say one way or the other unless we get a couple of side views -- it seems to me this would have been a nude statue (note no evidence of toga or cuirass on the shoulders) and I doubt greatly whether Julius Caesar ever had any of those made ...