Up to you.
But 300k is a 70's/80's thing in origin....not old school.
Vintage Jr's got either 500k in both posi's, or a 250k vol pot + 500k tone.
The 56 goldtpop got all 'nominal' 500k pots.
Higher values work better in the neck circuit, where clarity is preferred. In the bridge there is already plenty of that so you can afford to tame it with lower value pots.