[RichardJ]

The Vintage Air drawing is very similar to the factory, but the crank pulley will not work.
The alternator is being driven at two different speeds at the same time, because the outside crank pulley is smaller.

Mine is also similar to the factory, but no part numbers, because I scrounged pieces from various wrecking yard engines and modified the 250 PS bracket to fit the 292.
My Sanden compressor and the adjustment part of the bracket came from a VW Cabriolet. I fabricated the mounting to model the Vintage Air piece.

Paint a white line from the pulley timing Mark out onto the outside pulley. If and when the balancer rubber goes bad, the witness mark will no longer line up with the timing mark.

Notice the Vintage Air .pdf says "250 CID 6 cyl Chevy Point Ignition".
The HEI is too tall to fit under their AC bracket. The 292 is taller, which helps and I used the 1975 HEI with external coil.