Cast clutch fork, Does it take a special Throwout bearing?

[steveo3318]

Ok so I have had some clutch problems recently after a stroker build. I took a members advice and just purchased a centerforce dual friction clutch setup. Heres my question and its simple. In their directions it says to use a different bearing if I am using a cast fork. But I have already purchased an adjustable throwout bearing.

My question is whats the difference in a cast fork throwout bearing and a stamped fork throwout bearing? I am not concerned with the length. I want to know if there is a difference in the contact area for the fork to the bearing? Thanks