Off the beaten path: 35mm telephoto lenses adapted to 645

I've occasionally seen 300mm and longer lenses designed for 135 that have been adapted to 6x4.5. These are mostly vintage lenses. Are there any modern (late 70's and newer) 300mm to 600mm lenses that are known to have extra large image circles? Or, true telephoto lenses that don't cover larger formats but might if the lens head was adapted to a wider aperture barrel? I'm interested for covering the whole film area at middle distances for portraits, and covering a cropped 2:1 (6x3 cm) area at infinity. The existing options are gargantuan, and I don't mind some light falloff and softer edges.

I'm aware of most of the existing medium format options. I have the Mamiya APO 200/2.8. The 300/2.8 is interesting. But I'm curious about some of these 300, 400, and 600mm f/4 lenses from Canon and Nikon, etc.

The Schneider 360mm f5.5 Tele Xenar is a lens that covers 7"x5" it was also sold for MF cameras and 35mm. The CZJ 300mm f4 Sonaar was sold for 6x6 and was also sold for 35mm cameras, There will be many others.

Ian

The Schneider option is interesting. Their lenses from that age seem to have enormous image circles.

The one I'm most curious about is the Ai-S Nikkor 600/4 IF ED. It looks like all of the optical elements are forward of the tube behind the helicoid. It looks like that tube section could be replace and only the aperture would be lost, which could be replaced or omitted, while retianing the focus helicoid. But would require tearing one down to see if the tube itself is vignetting the image circle much.