Given this is a 700c bike with short reach brakes, I'd put a modern dual-pivot on the front. If you don't want to drill out the fork (fair enough), nutted versions are available.

Because it's pretty oldskool, I'd leave the original brake on the back. Very little point upgrading a brake that can already lock the wheel.

Vintage charm is all very well, but IMO the only place for a vintage front brake is on a bike that hangs on the wall.