Here are the choices: year unknown Ariel Red Hunter (sat up since the 60s), year unknown BSA Goldstar (ditto, same source), Road Star (normal, the Warrior is uncomfortable as can be), 1500 Vulcan (Drifter maybe), 800 Drifter, year unknown T100R (500cc Triumph vertical twin), generator Big Twin HD, 1950 Chief (same source as BSA and Ariel).
I've test sat Boulevards, Shadows and the V-stars. I don't like the seats on any of them. Except for a Drifter or Chief, anything else would be chopped. Even the Red Hunter. As long as it can easily be made into a running highbar...
I've already passed on a couple alternator case HD big twins. They leak too much oil for my taste.
Although...if the price is right...
-WD