I've got a 1600 xflow. I've seen oil catch tanks on other engines. Some seem to be connected to the rocker box on the inlet side and then
from the outlet to the manifold. Others seem to come from the PCV to the inlet and then from the outlet to the manifold. Am I reading this correctly?

If the pcv works by vacuum draw from the inlet manifold you need to pipe the outlet of catch can up to your inlet manifold.

You can remove the pcv, blank off your pipe to inlet and let the can breath to atmosphere if you want.