I like the idea of the spiggot on the tank. You can make one look antiqued by polishing one and then adding patina. The handles come painted but you might want to strip the handle and patina it too. The handles are usually steele rather than brass so that will be a matter of preference. You might get lucky on eBay. Sometimes there are antique fixtures that were removed from old houses before demolition.
To seal the spiggot to the tank (like a bulkhead fitting), get a plastic conduit nut from the electrical department at any hardware store. For gaskets, any Ace Hardware will have o-rings. Use an o-ring on the inside and outside of the tank. Assemble it all to look like the picture of the bulkhead fitting.