Cruiser Outfitters
This should help you if going OME. It doesn't have the stock rates. Actually the rates vary quite a bit by year and whether it had 3rd row seats. Even the number of wraps on the coils varies from application and year. Maybe one of the 4Runner guys has figured them out? The later model ones are using the front stock 80 coils to get about a 3.5" lift for their 4 Runners.
I hadn't seen your project before I'm definitely interested. I'm working on dropping a 60 body on an 80 chassis right now, I have a new set of OME J springs sitting on the shelf for that part of the project. But that isn't why I'm interested. I think I picked up another 60 today and I immediately thought to myself I need to put coils on it.
And I've been there and done that, hacking up an 80 frame for the mounts. A friend of mine is putting 80 suspension under his 55. It is a pain. However, I came away with a real respect for how stout Toyota frames really are.
The coolest suspension set up I've seen is a military jeep buggy running air shocks (no coilovers). It flexed awesome but what I liked about it is that it was completely quiet. The only thing you could hear was the tires squeeking on the rocks. No clanking or binding suspension sounds. It would be tough to engineer something like this in a full bodied wagon.
One last thing, dropping down on rocks with 80 front control arms is no big deal (someone commented on this). They actually slide better than leaf springs, especially if you have to go backwards.