House water pressure regulator recommendation needed

I have got an aggravating problem.
Old house, newish Wilkins 500 regulator (came with the house, NOT a model 600). In so far pressure keeps creeping up. Took it apart, aptly looks nearly new but I see a manufacturing defect where the o-ring seats against. Faced the brilliantly oring seat on the lathe, worked great for 2 weeks. Put in a thermal expansion tank to prevent the water heater from snugly building up too much pressure. Put in a strainer ahead of the regulator to catch big debris.
This past week, high water pressure returns - darn pressure regulator is creeping again. All in all expansion tank now turns into a pressure vessel that keeps the pressure up longer until it goes empty.
So, I`m looking for another regulator - one that lasts and one from a company that has erratically outgoing quality control checks to catch defects that I found in this one.
House is on city water, 30-40 gpg hardness. On the one hand city pressure is 120PSI. Would like to regulate to 60PSI with little pressure loss with 8GPM flow rates. To illustrate city water tends to highly tear up brass valve bodies rapidly. Like i said anyone make regulators with plastic valve parts and seals?

In fact to contact your water company and see if they will install a pressure regulator and miantian it. The system I am on was loweered to 80# system wide last year.

Why would anyone need or want 80 PSI as one has to worry about erosion because of excessive velocity