No MSD distributors use different diameter bushings to limit the mechanical advance and they have one that is totally electronic with pots to adjust the advance and rate. You will have to dial it in but I would not call that modifing it. For the most part any aftermarket distributor that is adjustable will be set up for a close to stock motor and require some adjustment to get it right for your set up.
One of the advantages with most of the distributors from MSD, Mallory, Accell, Pertronix, etc is they have a self contained electronic module. You do not need an external box like the orange or chrome mopar modules. This is also a disadvantage in that if they happen to fail parts aren't readily available like an all mopar system.Even the billet unit I posted a picture of uses the same pickup as a stock distributor so it's available at the local parts store.
Also the stock looking MP distributor with the vacuum advance has the same adjustable Mallory mechanism as the billet unit.
