I'm with the group that says it should be what the rider is expecting. Having said that I'll throw in more comments.

You might first ask how right-handed riders prefer them before determining whether to deviate.

All my bikes, tandem excepted because it is totally different, have the front on the left hand. It's how my first bikes were set up and AFAIK how those Europeans set them up all the time and they must know what they are doing.

Since I play acoustic guitar or maybe just because it is a genetically-inherited feature, my left hand is larger and stronger than my right even though I am right-handed. I don't think it matters much though.

I'll rig sidepull brakes with the lever and caliper ends on opposite sides so that the cable bend will be more open. Fortunately all my sidepull brakes have the cable on the right side for the front.

Finally, do not think in terms of dominant-hand or over-braking or preferring-rear-braking as pertinent. If you need to stop fast and you can't then you are cooked anyway, header or not. The fastest way to stop is with the front brake only because once you have reduced the loading on the rear it is more likely to skid. Well, you can use the rear but it will eventually skid as you brake harder, and some people have more trouble with balance when that happens. You won't take a header from rear-wheel braking but you can't stop as fast either. I have occasionally had to brake hard enough to lift the rear momentarily, and believe me when I say (1) I was happy, no make that delighted to be able to stop that fast, and (2) one's reaction time when the rear lifts is fast enough and the required braking time itself is short enough that a full header is extremely unlikely unless you are total klutz with the brake lever.

The tandem is different because it has both calipers on the right-hand lever, and a drum brake on the left-hand lever. But I generally use both anyway. It's a tandem so lifting the rear ain't gonna' happen and I need all the braking I can get.