SBC engine codes. What is it?

[carpoor]

By the casting #, it's a 283. The date code appears to be October 7th, 1964. (K = 10th month, 7 = 7th day, 4 = 1964)

Here's where things get weird, the XF code stamped on the pad references to a 1969 350 2bbl, 255HP, with a powerglide. The other characters don't follow any traditional GM pattern, other than the F at the beginning.