You might consider a "Platform" at the bottom of your (obviously) hollow tower. The "Platform" could House the beasty motor and would eliminate the pulleys. I would do any gearing in the gear box itself. The tension requisite on the pulleys, the cost of the pulleys/belts and the friction losses can and should be avoided if possible.
I am thinking a 6ft x 6ft x6ft platform. This would allow you to work on the motor w/o crouching, and if properly anchored should be more than adequate to support your tower. Or, if you are good with welding, you could make a "pyramid" style base from scrap I-Beams. In either case, direct drive would be simple to implement once constructed.