You can use a cutoff disc to cut the shaft after pushing the hub down like Larry said. First find a shorter pulley so you'll know how far to push the hub and how much shaft to cut off.

There are various pullies that will work. One is the 292 Ford from the 50s. Of course you don't find them in wrecking yards now like we did in the 70s when I did my first one.

Be sure to get a pulley close to the diameter of the late model 235 pulley. A smaller pulley will run your pump too fast preventing heat exchange.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.