I did a mix and match setup for short term after I rolled my toyota down a hill and bent 3 springs. I had several leaf springs from friends' trucks to pick from. I measured to find similar sizes and pulled apart the springs. You have to make sure the metal wrap infront and behind the spring pad is not damaged when taken apart (I can't remember the proper term). This keeps the springs from turning on the pad. I sanded and painted all the springs to make sure they would slide. I was in El Paso at the time, so there was not too much rust. Then I reassembled them.
I ran the setup for about two years with no major issues. I did have an issue in the front. I used the stock main spring and with the added lift, the length was shortened. I had a shackle angle that I didn't like. I replaced the front with a quality lift and did a crossover steering setup.
The rear is the same missmatch set up. After upgrading the front, I needed to add a 3.5 block to the rear. I run 28" slicks at the drags and 37" tires at the sand drags. I don't have any wheel hop in the sand and at times a little at the track, nothing major just a bounce when it launches, so don't be afraid of blocks in the rear. The truck runs 13.007 @109 with the exhaust and the hood and 12.520 @ 112 with zoomies and no hood.
I put 1500 Chevy rear springs on an 2002 Tacoma with no mods other than two new holes in the spring pad. If you measure and have time to locate some springs you will be fine. Make sure you take care and do a good cross over steering if you are adding a lot of lift in the front.
If you were closer I could help you out. I hope this info helps.
