A few thoughts from 10,000 miles away, Rene-
1- Bullet Cams is one of the easiest, most willing-to-work-with-you companies in the whole aftermarket world. Call them and ask for the owner Mike Jones. Be sure they realize this is an overseas call-
Mike Jones
Jones Cam Designs
Denver, NC
jonescams@bellsouth.net
http://www.jonescams.com
(704)489-2449
2- have you checked the cam chain? I've seen them worn out on a 351-C in 20,000 miles and a severe cam retard can cause odd issues
3- with incorrect cam possibilities, there are reverse-rotation cams made for dual engined boats, cams ground with GM's so-called '4-7 cylinder swap' that on a Ford V-8 is a 2-8 cylinder swap with corresponding ignition wires involved
4- The Pertronix box is the only electronic ignition I've ever found that can only partially fail but still run the engine.