I don't see where the shocks would be an issue unless you cut down the bumpstops. If you leave the bumpstops in-tact, there can be no more compression than before you swapped the springs.

That said, I can imagine a shock designed for the shorter springs would be stiffer to prevent encountering said bumpstops. A fellow employee installed a set of Eibach Pro springs on his Magnum without changing anything else. He said the ride was a bit stiffer, but he did not encounter any bottoming out. I plan to install a set on my Challenger.