Hello I have a set of BBC cylinder heads. The casting number is 3904390. The problem I am having is some say they are a 396 head and some say they are a 427 head. What are these things worht??? Any ideas would be great.

Mortec.com lists the casting number as...
3904390....67......oval..CLOSED..396, 427, 98cc chamber
...so both camps appear correct.