From what I know of Stewart-Warner, they used to dominate the market as you said. But, they always looked the same for years. In comes Autometer, VDO, etc. offering various styles......and S-W still looked like the voltmeter on your lawn tractor. I think they all but dropped off the face of the earth as far as the automotive aftermarket, but it seems that they have released some updated gauges.
If you like the style and the price is right, go for it.