Hi
Why do you want the hoist?
If it is for lifting engines from cars it needs to be very strong.
You should really check with a structural engineer to be sure but I used a 6"X5" RSJ built into the walls resting on a concrete padstone at each end, This RSJ was about 8 feet long.
It is helpful if the hoist is mounted on a trolley on the RSJ to assist in moving the engine away from the car otherwise you have to push the car out from under the raised engine,not always convenient. Finally, do you have enough headroom, the hoist and hooks and engine sling take up quite a lot of space.
Considering the various difficulties I would suggest a better solution is to buy a wheeled engine hoist which can be obtained at reasonable prices and can be used anywhere there is stable footing.
(The cost of an engine hoist is not that much higher that a safe geared hoist or chain blocks both of which hang down a long way)
regards
phil