What I have now on the 68 is a lower alternator bracket that bolts onto a bracket that bolts to the first header bolt. The top bracket has slots in it for adjustment and bolts onto the manifold. This may be a 1967 engine, and a aftermarket bracket.  It does not have the bolt holes into the head to support the alternator as in the newer models. My problem is that I am putting a lot of tension on the headers #1 bolt and even with the top alternator support with slots it the bracket the alternator  will not align correctly with the fan pully. What do I need for a lower bracket for support without having to drill bolt holes into the heads. Does anyone have pictures of their brackets for the alternator that do not attach to the bolt holes on the heads? This is a drivers side alternator. Some say it  needs to be on the passenger side of the 327-350 engine????? Can't go there?

This might help

It looks like there is a bottom bracket that ties into the top bracket, but there are no numbers indicating what it may be. This bracket would give support to the bracket that attaches to number 1 and 2 manifold (header) bolts. If that bracket exists and I can find it somewhere might be the trick. Thanks