The Commando 273 fins are glued onto the valve covers (not sure with what, but something like JB weld, which I don't think existed in 65) and can be (carefully) pried off and glued onto a set of two barrel valve covers. No need to fabricate new fins.
The only reason I’d like to mess with the idea of casting new ones is to have the ability to make another set later on. If it works well I might even consider selling the cast fins for others to use.
