Is the trac bar drop bracket installed? A 3 1/2" lift with no drop bracket and an adjustable trac-bar really isn't going to handle very well. Put the tires forward-- take a straight edge and measure out from the frame to that straight edge to make sure theres no illusion going on. Also is the lift a try 3 1/2"
I'm running a '76 on 35s with the 3 1/2 WH suspension, no drop bracket installed.
I won't install a drop bracket. Ever.
Fixed quite a few ripped out frames for 'others' back at camp with my mobile welder over the years though..
If you do want to change the track bar geometry, I always strongely recommend an axle riser. If you must use a drop bracket, you should completely remove the existing one and weld the doubler plates in the that frame are to carry the load.