Looks like a later, cast iron 4bbl intake. (you can see the choke well on the passenger side) so might be a 67 (ish). @serodgers66 , there should be a casting number on the intake that'll clue you in. Likewise, if you are curious, you can pull a valve cover and see which heads are on there. If it's running good.. keep it going!
Yup, that's a later spread bore manifold, ~'79 or later- that's when they went to the smaller diameter, diagonally bolted thermostat housing offset to the driver's side, instead of centered.
I see no evidence of an adapter or sealing plate, so I would agree it's probably a spread bore Holley.
