Upon closer inspection my used home I just bought has a 1" pipe coming in from the street (no existing PRV). It then branches at a tee that has 1" 3/4" and 3/4" fittings. One 3/4" fitting goes to the front sprinkler system and hose bib. The other one goes into the house.

I'm thinking of just buying a 1" to 3/4" reducer to feed a 3/4" PRV and the output of the PRV will feed everything as before.

Is this advisable? I'm thinking I will get reduced flow out of this setup VS. what is there already. But then I am installing a PRV to reduce the pressure which would reduce the flow anyway so perhaps this is a moot point. Any thoughts appreciated. Thanks.