I'd do 89 springs with mark's lift, but the key is that you'd have to get a shock extender (to prevent you from topping out all the time). That's just about the best you can do easily. We can't use a shock extender with 4WD, but with 2WD you can.
You can certainly get custom springs wound, but it isn't cheap, and you'll almost certainly run into UBJ issues if you go much beyond the 89 springs + 3" lift. The only way to solve the UBJ issues is a custom UCA like mine.
Regarding the custom springs, if you pay for the tooling and design, maybe you can come up with a spring length that works for a non-lifted TB, and can substitute for putting a lift block in - then you can sell it to the masses to recoup some of your costs. I'd considered doing that for years, but then Radflow came along and now I have no need.
The shock extenders look like the picture below. You'll just have to find one with the proper length and the proper metric thread for our shocks. I don't recall what it is though, M8-M10 maybe?