The first thing that he has to do is make sure that it is a 351, not a 302 distributor as they are not interchangeable. Then next, let us know which one he ended up with - there are two versions with Dura Spark and then an third with the TFS (it's actually the computerized Dura Spark but mounted on the side of the distributor. Here's a good write up on the Dura Spark:
http://webpages.charter.net/1bad6t/duraspark.html . As many Dura Spark modules have a 'history', often some run the GM version in a gutted module:
http://www.fordmuscleforums.com/igni...park-case.html. I've never had a problem so haven't tried this mod, plus am now using a full MSD system
As far as timing - 9-12 BTDC has always been good for the 351's that I've run and set with the vacuum disconnected though you really shouldn't see any at idle(vacuum line is PORTED/below throttle plates)