Yes, all the major brands, Walker-Turner, Delta, Atlas, Craftsman, offered slow-speed kits to do exactly what you want. They consisted of an off-center spud which fit into the column, a shaft, a 4-step pulley with bearings and a locking screw to hold the center spud in place.
Many of these drill presses used the same diameter column. You may be able to find another brand which will fit your W-T.
Once you round up all the parts, you'll find it finicky to get just the right length belts and then tight to change the belts from one step to another.
The good news is you end up with sixteen speeds. The highest three or four are way too high and at 16,000 RPMs the DP will take off like a helicopter for parts unknown.
thnx, jack vines