Stock Electronic Ignition or MSD 6AL ?

I would go with the Mopar performance Ignition , works great on the 340 in my dart sport. I tried a MSD box and had issues with it failing to work once it got hot, the Mopar stuff has been more reliable for me. even when the MSD worked it did provide a performance increase in a 12 second race car.

I would stay away from any Summit or other (like an HEI made to fit a Mopar SB) system, most of those house brand items are made to work with chevys and fords (mopars and others brands are sometimes included as an afterthought).