[Ziegelsteinfaust]

Be careful on the unstunistrut. Not all unistrut is equal. Some unistrut bends very easily. I belive the tall unistrut in silver zinc is the best, and painted typically is not the best.

Honestly if your structure is fine, and this is a good upgrade. Run box tubing across the rafters, and hang a small harbor freight winch on top. I would even suggest going as fas as to completely reinforce the rafters you choose to span.

This way you can support the load for a long period of time.
The winch does all the work.
You can use it to pull bodies off of frames.
Do motor swaps if you leave the chassis a roller

Just a though as for a bit more you can do a lot more.