I don’t see an MSD in the current catalog for our cars...
An accepted standard for electronic ignition for our cars is a Pertronix; cost is around $100 +/-.
And therein is the answer to why not just get a 123; it’s 4-5x the price. If your distributor is in good shape a Pertronix will be a worthy update to your ignition. If your distributor is worn, however, that’s a different story.