Why would want to keep the galvanized when it is notorious for failing over time.
I'd replace the line with copper, not plastic and have a new shutoff and PRV inside the building wall, not outside.
Having 140psi on that plastic line leading up to the PRV is going to be a connection put to it's limitations. That's questionable logic in itself even if piping is rated for higher. Crimp/banded/compression......it's got a possibility to blow out mainly for thermal expansion/contraction reasons. GOOD LUCK