[63HO3x2Cat421]

Hi all, i consider it a blessing i've found this site, and honored to be a member and hopefully learn from so many helpful & knowledgeable people. I've found what might be my dream car close to home, a 63 Catalina with(supposedly) a 421 HO 3x2. I going to see the car today or tomorrow, but have a question regarding identifying the block. Head number is 9770716, which seems to check as correct for a 63-64 421. Seller says it's not the original engine, but a 421 block, but i'd like to know what the actual displacement and possibly year built before i make an offer. Seller emailed me a few pics showing these numers stamped into the block on right side under the alternator: T 22 P, or possibly T 22 B. I see that 22 B shows in a book i have as being a correct block code, however neither the T or 22 P don't make sense. There is a bit of space between the T and 22 B. Directly underneath that code is a number stamped that reads 354996. It also appears there's another number stamped to the left of the block code but it's not legible in the photo. Since i'm new to this and not sure if i can make it happen, i'll attempt to upload the pic i have of these numbers. Any help would be greatly appreciated!
Thanks, Paul