I don't know if I still have a TBI "air pump" bracket. The trucks don't have 'em. IIRC correctly the pump is a lot smaller. I'll search for a photo, it will be easier than looking through my junk.
I read one idea that you use the two existing alternator bolt hole locations but use only one bolt hole for each alternator, clock them a bit, fab up a bracket for the others and a pulley. I was hoping someone has a link to a photo of a similar arrangement.
I'll keep in mind the battery tray from a diesel but the wife has a standing order to pick up any sleeping bed rails at the dump's "still good shed". I'm sure I have at least one pair left.
This one actually gives me some ideas...
http://greenbd.info/video/AZ7_HYtWS0Q/6-alternator-suburban.html