More info could be gathered from the engine suffix code In front of the head on the passenger side stamped into the block

I don't know the answer, but here's what spooked/impressed me: I went to google it, and as soon as I typed "GM engine" the autosuggestion was "GM engine family 113" so I assumed I'd found the answer!

But alas, the pages that came up didn't really have anything to do with engine family 113, but the formulation (guessing) of my search intent was pretty impressive. Must be gathered from the page content, I guess.

Took that pic does it help

I've got my original 1973 350 in the garage with the same casting number. That block was used in just about every Chevrolet car line and pickup and Canadian Poncho's. If its a 2bbl you have an L65, if its a 4bbl its likely an L48.

Well im gonna have to wait til i get it out of the motorhome cant see anything in there lol