I'm not sure if you're aware of this but with adding all those new parts, you could go to a u-pull-it yard and score a rear disc brake setup from an f-body (? 98 or so to 2002). It's not a direct bolt-on but it's not too bad. Here's a link if you'd like to look:
http://www.thirdgen.org/ls1reardisc The swap here would be the same for our cars. Only down side is I can't remember if these fit under a 15" wheel.
You can use the same prop valve FE3X CLONE used and it bolts in place of the stock one.
For a budget based front upgrade, you can do an S10 2wd spindle swap that uses stock a-arms. They have the dual caliper alum calipers and offer increased front braking. I believe these will fit a 15" wheel but can't say for sure.
Just a suggestion. I hate seeing anyone put that much money in a car unless you're restoring it back to stock, when you can spend about the same money and upgrade with much better parts. And, since all are factory GM parts, replacement parts are as close as the local AZ, Napa, O'Reilly's, etc.