Were you running lift blocks with the stock springs? If so, you need them with the chevy swap. In my experience, the chevy springs don't provide any lift, only more wheel travel and generally a softer ride.

More than tread lightly. Leave it like you were never there, nor anyone else.
'90 X-cab 4.88's 33 BFG AT's, rr ARB, Headers, Ignition upgrade, cold air induction.
'91 X-cab 5.29's 315's BFG MT's, rr ARB, custom bumper and flatbed