Thanks to @LPowell , I received a rather splendid anamorphic adapter at a very keen price. I've only just began testing with it, and yes it's got some quirks as all the adapters do, except the worth-its-weight-in-gold Iscoramas.

The rear lens element on the adapter is 52mm, which is also fitted with a custom step up for a 52mm thread size. This means my collection of Canon FDs bolt directly into it. 28/2, 50/1.4, 85/1.8 and 135/2.8. I also have the Panasonic 14-140, 100-300 and 14/2.5, which I've bought a 42 to 52mm step up ring for to attach the Century to it. Knowing that 14mm is super wide, I was expecting a complete mess of results and some serious vignetting. I was pleasantly wrong. It's far from perfect though, but in my mind, usable nonetheless.

I'm still testing the anamorphic. I'm keen to do real world, rather than test charts, so it may take some time. I'm a bit concerned over edge sharpness in some of my longer lenses, as first look seemed to be much of the same, although less pronounced. I do have a Tokina +0.4 Achromat to rig up somehow to the lens, which looks to help, although not for infinity.

Here's a very run and gun sample from the other night, and a few photos of the adapter mounted on the 14/2.5....which looks insane :-)