Help me identify what the hell I purchased :)

[Tellerbama]

Hey guys, new to the forum and have had a great experience so far.

So....I purchased a 72 C10 for dirt cheap. It was stuck in 1st gear and the guy offered me a price I couldn't refuse, so I test drove it in 1st and looked it over at nighttime in his driveway with my iPhone light. I was expecting to find a "350" stamp on the block but found 880 instead. I'm guessing this is a newer block. Im a bike guy and new to the truck thing so I need help identifying what the heck I have under the hood. I'll post pics and please comment on anything and everything you see. There are some obvious issues like electronic fuel pump hanging off side/not bolted, cracked exhaust manifold etc...

I want to know what I have so I can begin researching and starting off on the right track. Also, I'll need to address the exhaust soon and want to order headers so any recommendations would be excellent. I was going to order them before I found out it wasn't the original block and wanted to make sure whatever I order will fit.

Any and all input is greatly appreciated. Thank again.