If turning the aperture ring doesn't cause the lens to stop down when it's not on a camera, then it's probably something that someone hacked together and either lost the aperture blades when they made it, made it because the lens had no aperture blades so they figured "What the heck", or they wanted to shoot with it wide open only. To the best of my knowledge such a lens would have to be a hack (someone correct me please if I'm wrong...but a Zeiss lens on a Pentax 67 seems non-standard to me).

Regardless, probably the only way you'll find out what it's worth is to put it up on eBay and see what it goes for. (Without aperture blades my guess is that it won't go for much...it's a pretty specialized lens at that point.) Someone who has another 180mm Zeiss Jenna that they really want to mount on their Pentax 67 might be interested in paying something for it, but I think most shooters wouldn't have an interest in a lens that has no blades.

I'm sorry I can't be of any more help...best of luck.
Dave