JL,
I did this to my 12" crafstman saw about 10 years ago. I've since sold it on Ebay but is certainly worked very well untill I got something better. It requires a huge speed reduction.... I wanted it to run about 100ft/min and I think it originally ran about 4000 ft/min so I needed a 40:1 reduction. Or a 40" pulley on the saw and a 1" pulley on the motor......yikes! The final solution was to use a couple of jack shafts to ruduce the speed in more manageable amounts. See the photos:
I think I ended up using 3 -12" pulleys....1 on the saw, and 1 on each of the 2 shafts.
The performance was great! I was able to cut bars and ingots up to about 4" thick:
see photo:
By reducing the speed some 40X, you effectively increased the torque by the same amount and I soon found that the saw frame wasn't sturdy enough so I added several braces which helped out. I always had visions of the saw folding up under a heavy load.
One more pic:
The saw seemed to always need adjusting and tinkering with for some reason or another but served its purpose for many years. I eventually bought a big Powermatic 20" machine on auction that can be seen in the background of the first photo and got rid og the craftsman 12".
Just some food for thought...I hope it is helpful.
Sincerely,
Rob