I've been running 28s with a NR rear since the 70s. The secret is chain length. Setup so there is just enough chain to run on the large ring/28, though you wouldn't ride in that gear would you? Just keeps the derailler from being ripped off if you shift there by mistake.
The rub is because the chain is not short enough to pull the top wheel away from the freewheel. I've also successfully run 28s with the 70s Camp triple and a NR rear.
Ted, ain't no big thang if ya use yer head.