Welcome! Great looking bike!

Good advice has already been given but what does modernizing mean to you? Are you going for aesthetics or mechanicals? A black bike will adapt well aesthetically since modern components are mostly black.

If you’re aiming for modern components to change the riding experience then I think you made a great choice upgrading the brakes first. To my way of thinking the other major thing is the drivetrain. Do you want to shift from the handlebars or are you happy with the existing shift lever location? Once you’ve decided that you get into personal preferences and adapting them to work. To make it very modern you would swap to a 1xmulti-speed rear cassette. From there, post questions and the gurus here are glad to assist.

I think black deep rim wheels would look aces on your bike but that’s just my opinion. 🙂