If you'll scroll down the PGCA Reloading Forum there are several posts by Craig Larter and Mike Koneski, who occasionally look into the Forum here also
https://parkerguns.org/forums/forumdisplay.php?f=21&order=desc

re: safety of using pattern barrels, please review
https://www.shotgunworld.com/threads/is-my-gun-safe-what-load-was-my-gun-designed-to-shoot.366087/

I've never seen turn-of-the-century 8g pressures published, but it is likely that they were similar to 10g pressures.