Can't tell you how many times over the years I have seen them hooked up backwards. They run fine, but don't make max spark. I switch them to the correct positions and don't notice any difference. I assume that it does some damage to the coil from running it backwards, but don't really know for sure. I always put a Jacobs coil on everything eventually anyway.
Pump Gas Small Blocks Rock!
11.53 @ 116mph E85 408 at 8500 ft da,
3605 pound truck, 3.91s, street driven