On an f-body bracket arrangement the alternator sits low and tight. On a vette application it sits high and outside.
You can't mix the two.
Also, with an f-body pulley system you have more of a challenge running an AC compressor.
I like the GM brackets due to their low cost and proven performance. They look pretty good if worked on as well.
DSE, ATS, Billet Specialties, Street&Performance, Turn Key and Sinister all make aftermarket pulley systems of various prices.
It sort of depends and what accesories you want to run. Oh, my PM box is emptier now