<<A hub shell with cooling fins seems interesting, but I wonder if would have a real effect? A larger shell would carry a weight penalty >>
Elgin hubs were made with fins in the 40s. Dont know if it helps. More style than anything. The quality of these hubs rivals anything today . Made like a watch. The Bendix that everyone seems to think is decent is crap . Morrow, Old New Departure, Perry are all great hubs. ( many however have skip tooth cog and may be difficult to adapt)