I got adaptors on eBay from a chinese maker.
http://www.ebay.com/itm/282117297524?_trksid=p2057872.m2749.l2649&ssPageName=STR...These are a little funky, particularly in the top connection. The wire insulation does not go fully into the bakelite hole, so you can get a jolt if you touch the bit of exposed raw metal. I got them when I was first checking out 807s because they were cheap, had shielded silver wire going up to the top connector, had a silver plated top connector, and decent solder. The internal top connector is four prong and very strong, whereas it seems many are more relaxed fitting bent metal with gold plating and ceramic insulators. These connectors are so strong, I have to adjust them a little with a screw driver for some 807s with a little different top connectors. But they sound really good (good enough that I ordered more recently)!
EDIT: I don't think I was clear here. I don't necessarily like how strong this connector is, more commenting on how it is a bit of a hassle. But then, with minor "manual manipulation" they do fit well!I had ordered some back ups from the same seller, and they screwed up and sent me a variation. They seem to have the same straight forward bottom/pin setup and wire, but have a ceramic top connector with gold plated contact. The ceramic top connector seems better for safety, ease of use, and ability to change things if you wanted, but they did not sound as transparent!
I have tried a lot of tubes, and 807s are generally my favorite power tube in the Torii MKIV. But all power tubes sound different, and how they sound depends on the rest of the sound, so who knows how they might fit your setting. I would put them somewhere in between KT66 and EL34, probably closest to the Tungsol 6L6G (coke bottle next to the 274B in Steve's pic, my last favorite power tube), but the 807s tend to be bit clearer and more transparent if memory serves.