I have a short cage Superbe Pro RD on my 1884 Trek 760. I was able to get it running a 13x28 7 speed freewheel (52/42 in front). If memory serves, I had to make some B screw adjustments until I got it to hit the 28 tooth cog.
I'll also second the Cyclone GT recommendation. I'm running them on several bikes with 28 tooth cogs and they're flawless performers.