Another vote for leaving any +P stuff alone in your gun. Production quality varied a lot with those old guns. Some places produced good ones, while others had pistols that were built with slave labor and were poor quality, if not downright dangerous to shoot. (Hope you don't have one of those, btw!) You have a piece of history that is now probably anywhere from 68 to 75 years old. Don't take chances with it.
If you want to carry a hollowpoint load, you might want to try the Remington/UMC 115 grain one. Remington designed this load back in the 80s to sell to police departments and other law enforcement agencies that were still using old Smith and Wesson 9s and Browning Hi-Powers and other older designs that wouldn't reliably feed other hollowpoints. It has a rounded shape that is much like ball. I've run Speer Gold Dot 115s through a P1, but that was a gun that I'd done some "fluff and buff" on.