By the center of rim I mean that the valve hole is placed equally between the outer and inner beads of the rim.
In other words, if you stood the rim up so it would roll, turned the thing sideways so that you are looking at the inner part of the rim (you’d have the tire tread pointed squarely at your face), the valve hole is dead center between the beads.
If you have disc brakes, the caliper sticks out closer to the rim and the valve hits the caliper. Drum brakes are not a problem.
Just be sure you see the rims before you buy them. I lucked out and sold my freshly powder coated rims to VW guy that was not converting to disc brakes.
In all of this conversation, I am assuming you have a “ball joint” chassis that used 4 lug wheels. The older “Wide-5” configuration may also have the same problem, but those disc brake conversion kits are pricey compared to the 4 lug.