Big block + large rad + Mechanical fans = what fits?

I'm curious about what mechanical fans people are running? I have a 3 row aluminum rad. with 10" electric fans that I'm not sure if they will keep up.. I tried to fit a oem clutch fan.. but it stuck out to far and was in the rad basically...

A friend of mine was saying a Chevy clutch that has a shorter shaft will work has anyone tried this or know what works?