I just took a closer look at this lens, which I haven't tried to take apart for several years, and here's a little more info.

The optical surfaces are clean except for the rear surface of the rear element, which is hard to reach, because it is all the way inside the focusing tube. I've tried cleaning it with a long swab, but that never seems quite adequate, at least not for cleaning around the edges. The glass has tiny bubbles, which are typical of high quality optical glass of this era.

The rear focusing tube seems to be screwed into the rear threads of the lens and held with a set screw, but if you remove the set screw, it doesn't budge, at least not with any method I'm able to apply. You could use the tube to attach the lens to a small or medium format camera with a helical or bellows, as I've done with my Bronica, or you could remove the tube--cutting it off if necessary--and you'll have a shutterless lens for large format that should cover around 5x7".