Do all late model roler blocks have a machined cam gear area for torrington type bearings?

I'm researching for new timing chain and cover for a rebuild.

 

That would be a no. Theres a plate, but not machined for a bearing. The timing cover is the same for roller and non roller engines.

 

Can you reuse the old one of iss this something that sould be a new part?

I'll be runnign a roller cam and I'm looking into using a cam button and torrington bearings. How does this all work?

Doesn't the torrington bearing go between the cam gear and the block? If so then doesn't that make the cam stick further?

The "button" goes between the cam gear and the cover. Is there a standard button size?

I need some schoolin.