I have a 10 foot ceiling - and I wish it was taller on this 26x36 building. I am squeezed out what with both woodworking and mechanics equipment plus a disassembled 41 1/2 ton in it - there is no room to really feel comfortable performing cutting and swinging boards and plywood around, or sanding filler, and opening up an engine or other mechanical parts. The table saw with a sliding table consumes the floor space plus a woodworking bench, floor jointer and planer, wall mounted central dust collection with overhead pipes. Rolling toolboxes are around the perimeter - and the chop saw/cut-off station squeezes in the rest of the floor space.
The two activities are not compatible. (What would be compatible would be Woody Wagon restorations). So my advice is to keep the building as you intended and try to avoid mixing incompatible hobbies or multiple uses - guard it with your life - its not storage for the unused kitchen appliances, boxes of old picture frames or magazine racks from flea markets, a potting shed for flowers, and storage for upstairs bureau's that need to be chucked or old toys when the kids were 3 years old but are now in their 20's.
As for me, its time for a shop addition - just for the trucks and repair and maintenance of the tractor and yard equipment....to get this building back to to what it was designed for (woodworking). I plan to install a lift too and a 12 foot ceiling should be sufficient as you indicated for a lift and/or a gantry crane. My plan is to have 2/3 of the building with clear span/cathedral trusses (timber framed hammer beams) (other 1/3 loft) to give more than enough headroom.
One could go with pre-made scissors trusses with stick framing - to create overhead ceiling height too...without building 12 foot walls. They go up fast and relatively easy with two people - or hire a crane if you are not too worried about that cost. (the hammer-beam truss picture needs to be rotated). (the hammer-beam truss on the ground is what me and two others built at the timber framing school in June.) Good luck!
