Both the OEM (and aftermarket) EFI systems are sensitive to electrical supply capacity / quality, Bob. Ford used a stock alternator with a little over a 100 amp capacity with the OEM fuel pumps and other onboard electrical consumers originally for my engine.
By the time I added up my power budget for my fuel pumps, my electric water pump, my electric fan, the KB Boost-a-Spark, my Vampire detonation detection and correction hardware yada, yada I needed a minimum 200 amp alternator and a 900 CCA battery. I ended up using a custom made 240 amp alternator in a an OEM Ford Gen 6 small case format. It is the smallest case alternator Ford makes. The guys who built mine have all the different Gen 6 case styles so fitment should be easy.
The guys who built the alternator are
Mechman, (<=clickable), there are other good custom alternator shops out there also. When I bought mine they were offering a ten year warranty. Today it is less.
Mechman uses a high pole count, six phase stator with dual internal cooling fans and a welded twin internal rectifier design. Lots of words. Bottom line is that it puts out over 200 Amps at idle, has a 22,000 rpm upper speed limit and is the most robust alternator I have ever had — by a country mile.
Just like the engine wants ignition reserve to fire at elevated engine speeds the ECU wants electrical system power reserve to operate the engine at mid range and higher engine speeds. A marginal supply of power usually results in miscalculations of the engine fueling requirements — which in a blown gas engine usually comes with a price tag for burnt pistons.
The guys at Mechman are easy to talk to and will literally build custom just for your application. Almost forgot they can build this things as a self exciting single wire alternator which makes swaps like we do very easy.
Ed