Currently I have 2 IPK II's networked using PVA Cards. I can call back and forth between the 2. I am setting up paging using a trunk port on each system. Valcom V2001A on each system with a trunk port coming in. Now in the CCIS can I set up 5XX to use use a CCIS Trunk to acces the paging trunk on the other system?

As long as you have trunk access you should be fine.

On the i-series, Aspire, et al, I would make the trunk in it's own trunk group, then make a virtual extension call forward off prem using that trunk group.
With the CCIS you should be able to directly acces the trunks from either site.

Thanks for your help.