Good shock for lowered leaf rear

[tow rig]

I am looking for a good quality shock for a 1970 GMC C2500 with HD leaf spring rear suspension. The rear is lowered 4 inches with hangers and shackles. I have relocated the upper rear shock mount a couple of inches to the rear (to straighten the shock angle.) I have already acquired Bilstein sport shocks for the front (2.5 inch drop spindles.) I have heard of using front shocks on a lowered rear. I assume that this advice applies to coil spring rear suspension, and may not be applicable to leaf springs. Is anyone using a gas "handling" shock on a 4 inch dropped leaf spring rear? My preferences are:

1)Bilstein Sport
2)KYB Gas Adjust
3)Racetech HQ