The motor only has 152k miles on it. The head gasket was replaced by me in september of '11. I had the head cleaned and pressure tested, and while it was off, I looked at the cylinders, and they barely looked worn at all, i could still see the crosshatching on the cyl. walls, and there were no vertical wear marks. I put 24k miles on the truck, with regular LOF's, and it didn't burn any oil, and didn't smoke at all.
I have a "project" 300. Not sure if it would be what you are looking for, but here it is.
No idea of the miles on the short block, but the head is fresh from the machine shop. It was a decent runner but lost a timing gear. Gears have been replaced and a lot of work done to the head. The short block is together with the (fresh) head off. Also have a set of EFI exhaust manifolds to go with.
Drop me a PM if interested.
I am in the Portland, Oregon area.