HUH? If you can jack the car up to put on headers..you can remove two bolts and lower a cradle 3 inches.
More serious injury will happen from going under an improperly jacked up car (falling on you) than lowering the cradle incorrectly and dropping it out the bottom (maybe an arm or hand at most)
We did this exactly like the How to thread I posted yesterday. Great when it's all fresh. This weekend I'll zip off a bunch of pics to add to the write up.