Used to be Trailmaster had a pretty good Chevy kit, but I haven't looked at IFS lifts since I had my '98 and that was some years ago. Rancho used to make a pretty decent 4 inch kit, I always like it because the front/rear drop brackets were welded together. As long as the trucks frame is straight shouldn't have a problem with it lining up.
When I lifted my '89 I designed/fabbed my own brackets and put a solid axle under the front end. There is a company that used to sell and IFS to SFA kit, but it was expensive and then you had to source the axle as well, I doubt your guy is looking to spend that much or have that much work.