I don't know. Your numbers don't seem to jive with any that should be there. Here are two sites, which you have already probably looked at:

http://yblockguy.com/yblock_004.htm

http://www.ford-y-block.com/Block%20identification.htm

Are you sure this is a Y block? One thing that leads me to think it is would be the rams horn manifolds, those were used on some of these engines.

Very puzzling.

Don