Jerry,
This is the fifth inline 6 with clutch and bell housing I've done this way, one International, two Fords and two Chevy's all of them boat anchor motors (as far as weight goes) taken out and reinstalled with no hint of a problem. Using two bolts per anchor point and plate steel adapters eliminates any worry of shear. My ongoing concern is always the hydraulics in the jack in the lift which is why I never get a hand or fingers between the motor and and anything solid regardless of engine mounting points. No need to really anyways on these nice old inline motors just a push or a prod with a stick if need be will get them to sit nicely in there mounts
-Mike-