The condition I described was one of the weirdest ones I've seen. Plenty oil and clearance, and being able to spin it by hand and have it continue spinning like on rollers was just nuts. Had some bearing material not clung to the cam forcing a polish in the lathe, I dont know if it would have been discovered. That cam became a burr when hot.

If you have room to bore and hone the tunnel to 2.5 a ford roller bearing will get you to a 54.5mm core (BBF), or jesel sells a nice coated babbit for a 60 using that bore size.ive never done a factory block like that, so no idea about available material