What has worked out for me in the past is doing a shackle flip using Sky brackets. This with stock F-250 springs and blocks and 4" (or whereabouts, got 'em used)) lift springs in front along with a D60 made for a level lifted F-250. Shackles are stronger in tension, but you can box the stock shackles if you're worried. Rides a little harsh but with a few hundred pounds in the bed it's smooth, in the rear at least. Never had a truly soft or nice riding truck with lift springs in the front. I think shackle reversal is the way to a soft ride and good flex up front.
For my factory D60 truck I want to do a shackle reversal up front which supposedly gives about 2.25" lift, and probably add a leaf and/or re-arch the rear to match. Could use just a little lift to not scrub tires when tucked and I'd like a nicer ride up front. Want minimal lift to accomplish that as ground clearance is already sufficient for my needs and I like a reasonable bed height for loading/unloading.
For what it's worth my F-250 lifted as described above has 3" more axle centerline to fender clearance up front than my stock F-350.
