[Rooster's 67]

the sd508 is a very good compressor, and the brackets work very well. which brand are you looking at? They sometimes will require a little tweaking to line the belt perfectly to the others(trimming of bracket or installing washers). But they generally are designed to work with manifolds or headers.
Another issue that personally I do not like about the pass alt/drivers ac is why run the ac lines all the way across the engine bay?

These kind of "street rod" brackets sometimes end up with a loooong unsupported belt on the slack side, which can cause tossed belts, especially in a performance application