Not sure on a ZR2, But on a regular S10/4.3/4L60E......Remove all body mount bolts, Lift the Cab & front clip/core support 1 1/2" & put small 2x4's between all cab mounts & cab, Have the radiator/fan/shroud out. Un-clip brake lines & harnesses as necessary.
If a ZR2 has a factory body lift, Nevermind
Anyone that say's they put a 4.3 in a S10 without lifting the cab has a hand full of bolt/nuts left over when their done