Check that the alternator is capable of holding proper voltage under load. The procedure indicated by Sick, is the proper procedure for testing alternator capacity. The one thing he didn't mention is that you should also check the voltage under full load by turning on all accesories & lights. The battery, without the alternator connection defaults to 12 Volts, a good alternator will maintain 14 Volts under full load. May have to get engine around 1500 RPM to run test.

As for the MSD replacement, I haven't had any personal experience with it, but I remember a post where the person that bought one, could not get the car to run. The one option I am familiar with, and heard good reports, is the Delteq 8 coil conversion. This sytem retains the electronics section of the Opti, but handles the high voltage portion outside of the distributor. Most of the Optispark problems are caused by dampness and ozone concentration, which combine to corrode the Opti internally. I assume MSD is using bettter materials, otherwise it would be a waste of money.

This is a link to Delteq http://www.delteq.com/