85 PSI is too high. 60 to 70 would be better. When you install a PRV, it is a good idea to install the expansion tank, becasue you may have a closed system now.
As far as the clicking noise, some GE/Rheem?Ruud models were prone to this and it related to a ball check heat trap nipple. If you have one of these, Rheem will pay for a service call to have a plumber replace with flapper-type heat checks.