Dropped spindles will move the truck down without changing the i-beam angle I do believe. But you get more drop yet with bent i-beams and shorter springs.
Now, prior to a certain year, when they changed to cast i-beams, you can heat and bend the stock i-beams to get the correct camber. But I don't remember what years so you'll have to research that. That's the alternative to getting dropped i-beams since you're into heating, lol.
That's been done a lot and if done carefully doesn't weaken things too much.