Tonight I finished the speed reduction. I bought a 7" and 2" pulley, 12" of 5/8" round bar, and two pillow blocks from McMaster. Last night I milled keyways in the shaft. Boy, 12L14 steel is nice to machine! It cuts as easy as aluminum. Then I mounted the pillow blocks to the shelf using 2x4 wood spacers:
Tonight I mounted the treadmill motor, which has a variable pulley that goes from 1.75-4.5" OD:
The motor is mounted on its original mount from the treadmill, which allows it to pivot and vary the pulley center distance, which pulls the belt in and out on the spring loaded variable pulley. I went quick and dirty, and mounted the pivot shaft on Adel clamps (cushioned cable clamps), and a bit of threaded rod screwing into a brass trunion under the table to make the adjustment. I had the same setup on my old bandsaw; I sold it with its original motor and kept this one.
I now have a working speed range of roughly 350-1100 fpm, which is perfect for aluminum, and usable if a bit slow for wood or plastic.
Then the wiring, and the saw is usable. I still need to make a replacement for the missing motor wiring cover, and then finish the table pivot, but I can use the saw as it is to work on the pivot.