New purchase, lots of unknown

[jr2k3_esq]

Hello!
It’s been a lot of years since I’ve posted last, a couple of weeks ago I picked up a 1972 GMC Suburban 1/2 ton and need help figuring out what’s under the power barn. I’ve been told it’s a 496 Big Block, it has a Holley Carb on it and Edelbrock performer 2.0 intake, and signs that someone was playing around on it with bolt ons. Looking around online at how to read the engine stamps I can’t find this one. I’m trying to figure out if it is a factory 496, or the more likely 454 punched out. Or maybe the information I had gotten was wrong and it’s a 396 🤷*♀️.

In that regard when it comes to me looking to purchase parts for it, would I tell people it’s a 454? Any help would be appreciated.

The number on the tab on the front passenger side looks to be 071175266