I've run a few on cradles
. I can't weld, and don't fancy investing a heap of time in switches etc for something that will run for short periods infrequently... that means my way is pretty simple.
Simple way is to buy a SBC engine cradle - you can get these from Radum. Make sure you get the one where the rear (angled) legs are moveable, not fixed.
A piece of RHS drilled and bolted to the front allows you to pick up the front engine mount, with or without the Holden rubber pillow block. Sliding the legs backwards allows you to pick up the rear Holden steel gearbox angled mounts. This works both with the engine-only, and with a gearbox in place. handy if you don't want to separate them.
If you are only firing it up to keep it turned over (or fiddling with float levels etc), you don't need a radiator. Pull the thermostat out, and use a cutoff length of bicycle inner tube (with hose clamps) to fit your garden hose into the top thermostat housing. Another length of inner tube on the lower thermostat housing will let you get the water to drain (or at least away from the engine). Take the four bolts out and pull off the fan... it hurts if you accidently put your hand into it!
If you are trying to tune it (jetting or timing), you will need the thermostat and radiator to get it warm. Bit fiddly - easier to tune when the engine is back in the car... the time it takes to plumb a radiator is really not worth it (at least to me).
Wiring is pretty simple - negative jumper lead to engine block, small hot wire from starter to coil, positive jumper lead to starter with small hot wire attached. Touch the small hot wire to the starter solenoid to get it to turn over, then pull off once it fires.
Fuel from a plastic bottle, run through garden hose into either the fuel pump or straight to carb (wire the plastic bottle above the engine to let it gravity feed). Don't forget to remove the bottle lid or it will pull vacuum and starve.
Exhaust out the standard manifold to the floor. A bit noisy (and some 1' flames when backing off) but that's half the fun.
Cheers,
Harv