Also, not to turn you away from bowfin-if you can find one and get a big enough tank, go for it-but have you checked out bichirs? They are somewhat similar to snakeheads, but are legal and some species are much smaller (so wont need a huge tank) and readily available. Check out the Polypterus section here:
http://www.monsterfishkeepers.com/forums/forumdisplay.php?f=108
Not trying to talk you out of a bowfin (I plan on getting one myself eventually), but if you can't get one for whatever reason, bichirs might be an alternative