Whatever you want. It's your bike. Those that want a bike all original are treating their bike as museum pieces, not that there's anything wrong with that.
"Back in the day" there were a lot of production bikes that were purchased and upgraded before a single mile was ridden. Proof of this is my first "real" bike purchased in 1975 - Raleigh Super Course MkII.
I rejected original equipment then.
As far as period correct goes, why limit yourself? I've built up several vintage frames with more modern componentry. If a bottom bracket is pulled out, I almost always replace it with a modern sealed model. I'll use OEM or period correct parts if they're good.
You'll get many opinions here, but at the end of the day, just follow your bliss. If riding on original equipment makes you happy, do so. If you prefer the performance of a modern part, go for it.
The only rules are the ones you place on yourself.