The front half of the lift will work (IFS part). The rear is different on the older trucks, they had shorter rear leaf springs, other than that the kit will fit.
the 89 ifs is the same as all first gens, if you wanna go cheap you can just crank the torsion bars, just keep in mind that youll only get a few inches and your ride will be rougher, which defeats the purpose of keeping the ifs. most of the lifts you will find that are for sale are add-a-leafs for the back and a bracket that lowers the front axle from the suspension, so you can fit big tires but your not gaining any flexibility.
i know about the torsion bars. he wants to go 35" tires so we was thinking 4" suspension and 2" body with minor fender trim. the rear lift will be easy. maybe some 63chevys and shackles