328 Oil Pressure Regulator Specs?

Anybody have specs on the 328 oil pressure regulator? I have the spring specs from the manual. But I am looking for the diameter of the plunger and the sleeve it rides in. Mine has a brass sleeve in the housing, I assume this is stock?
If I take mine out and then slide the plunger back and forth a little by hand, it seems to stick a little. I have oil pressure jumping around at constant rpm - which would either have to be the pressure sender (most likely) or the regulator. (guage is tested and fine, as well as everything else on the electrical side) Already replaced the sender - though it could still be bad because I got an aftermarket one which I believe to be crap - so a new marelli one is on the way.
I have the engine out at the moment to check everything over - better safe than sorry. So I am wondering if while I have it out I should do anything with that brass sleeve, like replace it. But it isn't even in the parts manual?
I didn't get a chance yet to measure the spring, which of course is a likely cause of the problem. I would just like to also measure the inside of sleeve to see if it is worn. And make it slide easier without it feeling like it wants to stick. Maybe I'll at least try to hone any ridges out of the sleeve while I have it out.
If anybody has an old plunger/spring they want to sell, let me know. I'd be interested in reverting to the old part just to do some testing - mine has the new updated plunger and spring.
Thanks in advance.