OK, so most of the lead is on your belt, so don't worry about the floating your rig thing. With 27 pounds of lift on the wing, it can support roughly 27 pounds of ballast on the rig. You are bringing much less than that on the rig, so you'll be able to float it no problem. 27 pounds should be plenty of lift for any setup in this area, except maybe heavy double steels with a thick wetsuit -- but heavy doubles in a wetsuit is a bad idea in the first place, and doubles would need a different wing anyway.
Well, if you are getting that from comparing to my numbers, there's a grain of salt there. Because our bodies aren't the same, and I don't dive a 2-piece wetsuit, I either dive a one-piece 8mm wetsuit, or a drysuit. I guess my wetsuit would be the closest thing to your wetsuit... for that I use 16 pounds lead, 5 pounds from the steel backplate, and 1 pound from an empty steel tank. So call it 22 pounds total ballast.
Your aluminum plate is probably 1-2 pounds ballast, HP80 is about 1 pound when empty, so that plus 15 pounds lead is around 18 pounds total ballast. If you are having trouble sinking, especially if you're having trouble at the end of the dive, then yeah adding a few pounds lead is probably a good idea.
One thing I will point out with your numbers is that a 9-pound gap between HP80 and AL80 doesn't quite add up. An HP80 is about 6 pounds more negative than an AL80, so when you have your weight dialed in, I would expect a 6-pound gap between the two setups. Have a look at the tables in
this thread for more info; the relevant quantity here is the buoyancy when empty.