As a follow up, I installed the Pertronix digital rev limiter after confirming its compatibility with the Ford Duraspark system. It was an easy and hassle-free 3-wire hookup and actually works quite well. Set at 6K, the first burp came in at just after 5900, which could just be the accuracy of the Smiths tach.
I've heard of the woes with the Duraspark but until mine starts to show problems, I think I'll wait before swapping with an MSD. So far, it has worked flawlessly.
