This does look to be a BB Chevy intake. All the visual evidence i.e., bolt patterns, dist. hole location etc. appear correct. BB Chevy intakes always look narrow due to the large size of BB Chevy heads. I've had a few BB Chevys in years past along with several 455 Olds powered Cutlases (prior to marriage of course!) It does'nt appear to be an Olds, those 455 intakes look a mile wide & the bolt pattern is different.
Could this be a "marine" application ??
I know a few hot-rod boat freaks here in Mich. I'll ask them.