Here’s my 1979 Custom Cruiser 403 L80, Vin code K lay out. This one has a period correct R4 a/c compressor on the passenger side (the front compressor bracket is missing and I put a piece of flat stock there to hold it steady), and the Tempmatic air conditioning is visible on the passenger side firewall. On the drivers side, the alternator (a period incorrect 12SI, they came with 10SI) is in the usual configuration. The cruise servo is directly above the oil pressure sending unit (an oil pressure switch on non gauge equipped cars), between the alternator and upper radiator hose. The cruise transducer is on the drivers side fender well. This one is no where near as pretty as yours, but is typical of Vin R (350), and Vin K (403) layouts 1977 through 1979, and very similar to 307’s through 1990. Even the 307 equipped Cadillac Fleetwoods looked like this through 1988 (at least), complete with the level ride air compressor next to the radiator on the passenger side above the EVAP canister. The 77, and 78’s would have come with an A6 a/c compressor (the long one). If I’m not mistaken, the Omega was the only Olds left with an A6 compressor in 1979.
Anyway, after seeing and working on (quite literally) thousands of them, it caught my eye and struck me as odd. Sorry for the ramble

The second and third pictures are of what the gauge package looked like in (at least) 77, 78, and 79.