Killerduck,
Dont know if you have your heart set on nothing but a Seminole tube but I have been running Briley's for years with great results.
They make a spreader choke, it's .005" constriction and is rifled. They call it the "Diffusion" and it does wonders at the close in crossing rabbits. With it being rifled it imparts a twist/spin on the wad as it exits the muzzle and quickly spreads the shot colume. I cant say enough on how good they work.
Here's a link that will list the various makes they offer.
http://www.briley.com/chokeselection.aspx
Briley serves the entire world, here is a contact for your country....
Greece
Touris s.a.
(Briley chokes and accessories)
17th EthnikiO dosAlthinon-Lamias, 2 Pilou St., GR-145 64, Kifisia, Greece
Phone: 3-210-8002-444