That's a bit weird but anything can happen. We have run MSD stuff, heck maybe 25 years or more and other that a bad ignition toggle switch killing a coil never had any problems that weren't self-inflicted.
You asked about the converter. Not sure if you checked your current stall speed but find a flat, level road area and let the car coast along at 15-20 mph with it in high gear, then whack the throttle hard and watch the tach - what it jumps to is what your stall speed is with your current combination.