Almost impossible to find factory air compressor brackets for a 348 or for a 409.
I could not find one for my 409 so I purchased mint repro assembly from Show Cars Inc.
I suggest buying a new compressor bracket assembly from Show Cars Inc in Minnesota.
here is the bracket assembly for 348 motors
triple upper water pump pulley needed.
triple lower crankshaft pulleys
Show cars sells the pulleys also -they are high quantity reproductions
Paul