I originally had a high-time O-320 E2D on my 9A. No problems at all. When overhaul time came, I swapped the engine out for an ECI Titan OX340 stroker and it fit up great as well. The only thing the "same front" comment applies to is the front main bearing inside the crankcase. It's a split (4-piece) bearing instead of a 2-piece bearing with larger halves. No physical difference at all for fit or installation.
Probably the only thing to be aware of on the E2D is most of these engines came off Skyhawks and therefore don't have fuel pump provisions on the accessory case. You may have to remove the accessory case (easy), send it out to be machined, and purchase a fuel pump gear and pushrod in order to use a standard mechanical fuel pump. This is a relatively simple conversion.