I've done enough Chevys to know this. I think... After water pump is mounted then goes steering pump bracket, then AIR pump if you have one, (Won't with headers LOL) then A/C, and last alternator. It really all falls in to place once you start holding things up. Just part of the fun of getting it back together- the memory test.
I did get wise when I took my Olds 350 out of the Delta, and took about 20 detailed digital photos of how it was mounted in the Delta along with the bracket mounting as I tend to forget things once they lay apart for more than a week or so :?
-UT-