[mbelan2]

This is my first post to this forum and I am in hopes that some of you FE enthusiats will be able to help me out. I just took possesion of what I was told was a 391 from a 1967 F600. I disassembled the engine and became confused with what I found. It seems that I have a 428 block that was only bored to 4.05" with a forged steel 391 crank 3.78", D2TE-EA $E. I only know this block as a 428 by the casting inside the center freeze plug. What kind of mongrel do I have here and which direction should I go to rebuild it, 391 or 428? Thanks.