I have attached a pic of the A-C compressor brackets from the ’63 Oldsmobile Service Manual. Note the brackets are different for P-S and regular steering cars. It is possible that British Leyland, Rover, A-C compressor brackets might work for you too. The 215 block B/L made was the same up into the ’90’s, but I do not know if they mounted the compressor in the same place on the block? That would give you a lot more offerings to find a mounting method for your application in a salvage yard.