Pontiac block decoding

[ClassicCar.com]

I have tried unsuccessfully to decode the 455 block in my 1969 firebird. I am looking for some assistance in this. Stamped on the block is the XJ code, which reads for a 428 1969 block, or a 400 "B" body block from 77. HOWEVER the 455 stamp is readable on the under side of the block near the motor mount on both side of the engine. I can not find an XJ code for a 455 in ANY year. The heads are somewhat of a mystery as well. They are casting # 62 with a code of F069 stamped on them. Obviously the 62 code was used regularly throughout the years. It's hard telling what engine the heads came off of. Any help in this would be much appreciated. Thanks!

-Jason

[ClassicCar.com]

Jason, I've found an XJ listed in my Motors manual. It lists it as a 428 with a 4bbl mated to an automatic. The manual aslo indicated it's one of three HP configs 360,370 or 390HP. It does not give an indication relating to which HP rating is for the XJ engine though. I hope this helps in confirming your findings.

[ClassicCar.com]

It's a 1969 Pontiac 428 that was mated to an auto trans. For great Pontiac info got "ClassicalPontiac.com"

Bob

1965 Catalina
1966 Grand Prix