I’ve run the Mallory Unilite conversion in the ’57 distributor in my ’55 Customline with a 272 for well over 100K miles with zero issues.  Spark plug life is incredibily good and change them at 45K miles just for the sake of changing them.  I also run the Mallory Unilite distributor in my altered roadster with the same high level of performance.  The Unilite modules use to be sensitive to voltage spikes or loose connections but I understand that the units made within the last ten years or so are much more robust in this regard.  As Chuck mentioned, the Unilite distributors do not have vacuum advance capability but using the conversion kit within the Ford distributor allows you to retain this capability.

No issues with the MSD line of distributors either.  Also have one engine with a Pertronix on it and although not a lot of time on it, runs well.  Anything is ultimately better than points after it’s all said and done.

            You need to modify a curve anyhow, 10 to 12 initial and only 30 to 32 total with the blower. Vacuum advance will work if it's plumbed into the manifold below the carb.

I assume your talking about the 57 up dizzy. You mean their is enough vacume signal below the carb to bring in the advance with the blower boost? I can recurve my 57 Pertronics unit and try that. I still wonder if the Mallory unit is part of my problem. Its been on the last 3 engines. None of them had the pull they should have. At this time I dont know anyone in NH that has a machine to check the dizzy for me. This should be an interesting winter! Chuck

            You can set the timing on the car with a light. Just mark the damper with something easy to see with the timing light and use that. you are looking for a total, with the blower of 30 to 32 degrees, no more.

       The vacuum will work only at idle and cruise. when you open the carb, the intake pressure will rise to blower pressure and the advance will not work. It only can work when the intake pressure is less thamn ambient. In other words a vacuum . And yes, I was talking about the '57 distributor. Weld or solder one of the slots in the advance plate up and then grind the slot 'till it gives about 18 crank degrees with the light. That's 9 degrees distributor.