Who's suspension is under it being 5"? Is it Rancho?
Most mfg's are 2.5", 3.5", 4.5" & 5.5" for 66-77 Broncos.
If you do have Rancho or some thick coils up front you might look into replacing them with some modern day long travel coils for $130/pr.
Makes a huge difference in the ride, much softer. Then use 70/30 shocks like Duff sells, they are chaep and work well.
If you have these already, I guess I got ahead of myself again...
Will you be off roading this Bronco often?