I would agree with that choice. I have a GM HEI distributor and installed the MSD 6AL Super HEI kit. I saw no difference in performance. I installed the MSD box under my dash and the only thing I got out of it was a noticeable hum(they're not overly quiet). Also, I was doing some reading after I installed it and learned that you lose the multiple spark feature of this box when you run it through your GM HEI distributor. You can only have a single spark with that setup. Has something to do with the ignition module or something like that. The person who wrote it actually contacted MSD about it and they verified that it was true. So after reading that, I was like, "What the hell am I using this thing for then?" The only feature I was truly getting was the rev limiter. So I removed it and went back to my standard HEI coil and ignition.
I know this doesn't really answer your question, but it does support your efforts!