The retainers are determined by the springs ... the o.d.and i.d of the outer coil and the i.d. of the inner coil if there is one. The valves will determine the locks ... the valve stem size and how many lock grooves the stem has. You will have to decide between 7* or 10* retainers/locks up front ... I'd go with 7*.

I'm pretty sure all this infor is listed in the head specs on 440Source's site.

As for what they have to do with the cam ... nothing really but those items are the "weak link" on the 440Source heads. For about $85 you resolve the issue.