If you are interested in efficiency you only heat as much working fluid as necessary not the whole pot.
Minto heated the whole mass and not just the 1 or 2 percent needed to pump it. Lousy design.
Also everyone seems to be missing the fact Minto's wheel is a thermally driven "water wheel"
water wheels are gravity wheels and need to descend slowly as the drop needed to accelerate to rim velocity is lost.
So reasonable power means LOTS of mass. That means big containers and large pipes. Large pipes represent loss too.
whats in the pipe is not in the upper tank. So that means slower yet as all that mass has to be transferred before you move very far.
Torque - you bet. Hard to harness when they get too slow.
Pencil it. Small wonder it was given away.
There are a number of different setups that will work but just about all of them work better than the original. It all depends on what you are trying to use the wheel for. It would be very good for operating a water pump or grain grinding device. I have drawn up a number of different versions that I think would all work better and faster. Check the link to see the pics.
http://www.leebell.net/workshop/minto1.htm (http://www.leebell.net/workshop/minto1.htm)