the v8 only has 4 mounts, two on engine and two on box
if you remove either unit, th eother will swing around and break its rubber mounts off probably.
the other unit needs good support if it is to be left in the chassis
when i remove my gearbox i put piece of wood behind engine against bulkhead, it rests there just fine.
if you have no body on, i would use ratchet strap to create sling under either unit to support one end of it maybe
all you need to do is stop heavier end dropping, mounts will take the proper weight
cheers