Well, "64" is a Giro d'Italia, and "40" is the width. You might like "66" (Campione del Mondo) in a "42" width. I'm not sure it comes any wider than that. Here's a potentially useful eBay search. (To fill in the gap, "65" is a Criterium, which has a more track-like transition from tops to hooks.)

You might also take a look at the 3TTT Merckx bar.