I own that same exact intake. It's a 63 low rise intake, most likely off a 406 Galaxie I was told. I bought mine from ebay as well. The guy had it listed as a 428 PI intake, so I bought it like a dumbass, instead of doing my homework. I paid like $350 for it I think. But after talking to some FE gurus, I was told it's a good intake for my FE Cobra build up, all I might need to do is port match the ports for the Edelbrock heads. It was also in perfect shape, no cracks or damage, and had the metal shield still on it underneath. I was told I paid a fair price for it and it should perform well. Also, it has the proper look for my 427 S/C clone build. The 428 CJ intake does NOT have the
oil fill tube, so it wouldn't have had the look I wanted anyway. The CK8 number is just a casting code, mine says something like EF6. the rest of the intake is identical. Mine does have the casting number on the number 1 intake runner though. Maybe a previous owner of your intake ground it off to try to pass it off as a later CJ intake.
Hope this helps.
Sal