Hogue, your answer is a little confusion I guess :)
WC_Collaboration has the Jive software on it for the discussion services
UCM_server1 has the content repository on it (WebCenter Content) that will store documents + wiki's + blogs.
WC_Utilities has the analytics and personalization engine on it.
Therefore,you want to use PS5 webcenter framework and PS4 UCM.
you can point PS4's UCM_server1 in PS5 webcenter framework.
But it is suggested that you use same version for both the cases.
If you have any blogs+ wikis stored in ps4 UCM_server1 then migrate it in PS5's UCM_server1.
Even if ,you don't migrate then also you can continue with your previous version of ucm.