iirc 4crawler stated suzuki samurai stock shocks are what you used for the front with BJ spacers.

If the lift springs for the truck are THICK leafs then it will ride like a bucket of bolts-to stiff. T-bars as already mentioned are stiffer as well.

If the shocks are older than 40k or so replace them, I replace mine every 50k.

As for tire pressure, if you want to get exact you can draw a chalk line across the tread and drive straight at different pressures till the line wears off even. Or you can do it the guessing way and drop about 10-12lbs from max pressure. IE my T100 rides on 265/75/R16 bridgestone dueler revos, max press is 50, I run 35 up front and 37 rear and it works great.

My truck also rode VERY hard and had this insane vibration till I figured out all the cab mounts and motor mounts were shot as well as the mounts for the front axle setup. Replace all of them and WOW it rides smooth.