The pulley on the tongue is for the hand clutch release chain used on a JD two cylinder. They where called "knee knockers". If the plow tripped the hitch and the plow "unhooked" the chain would pull the hand clutch back or disengaged the tractor clutch. There where some brackets needed for the tractor but that is what the pulley was for.
Your plow is a JD 44AH they where made between 1945 and 1957. Yours is later than a 1949 because of the hitch. It is earlier than a 1953 for the same reason.
As for value. They are bringing more money that just a few years ago. The popularity of plowing days is causing that. I would say that plow could easily bring $400-600, maybe even more with the new points and all. It appears to be complete with rolling cutters and cover boards. It also had all rubber tires they are worth more than the steel ones right now. Guys can parade them easier.