20" clutch fan

Is anyone running a 20" clutch fan on a SB with a 22" radiator? I knew I had a clutch fan in my parts stash but was shocked to see how big it was. It was off of a late 70's C-body with air. I know I'll probably have to get the shorter clutch but I'm not sure if it's too large. I'm probably going to run a 3 core Champion rad.

I obviously have to mock things up to be sure. I just wonder if I should pick up an 18" fan and not mess with this 20? Is the bolt spacing for the clutch the same for the 20"? I'm wondering if the big fan will hit the rad hoses.