Greetings from Oregon. My first car was a 1956 Merc Montclair 4dr htp Phaethon, 312 auto. Bought that in '68 for $25 with a bad starter and a blown head gasket between 2 cylinders, Fixed it and what a great running car. Must have been owned by a little old lady who only drove it to church on Sundays lol! It's long gone and fast fwd to now. I know very little about Y blocks as the '56 Merc, a very short stint with '57 F100, 55 Ford wagon with a 272,and a '54 F100 w a 239 were all owned in the late'60's. My brother recently passed and his '54 Sun Valley apparently has a bad engine. It has been in shop for sometime and his intentions were to modernize the drivetrain which I am totally against. He said the shop guys told him they couldn't get the parts to repair the 256. So I've been studying the situation trying to learn as much as I can about parts, interchanges etc. It will be a couple weeks before I will be able to see the car and talk to the mechanics but I want to be armed with as much info as possible when I talk to these guys. My understanding is the '54 has some differences, fuel pump, cam bearing diameters and cam gear teeth. We would like to put the 256 back in but thinking if it's too far gone or finding parts becomes difficult or too expensive a later 292 might be an option. So this is the same bore as a 272 and I'm not finding a lot 272 rebuild parts. I guess for now I'm looking for someone in the Portland area who could possibly go through this engine or someone who could share their knowledge of these. The Portland swapmeet is just around the corner, I have a space at Expo and will be prowling there and PIR. If any of you experts will be there maybe we could get together and discuss a solution. 

Any info will be greatly appreciated, 
Dick