I am selling a very nice Komura Commercial 300mm 6.8 with the original hood. It's a tessar design but I can confirm that it indeed covers 8x10. Unlike some older Tessars I think this is at least single coated so it does well with color. The only flaw is a small bit of what looks like separation in a rear edge. This has made no differences in any of my 8x10 images.
The Copal 3 shutter is accurate to the ear with no issues.
I bought it for $400 and I'd like to sell it for $400 net to me.