The original alternator and regulator system was adequate for these cars. I sold my 1968 back in 1974 and never had any charging issues at 50K miles. If you don't add accessories such as an electric cooling fan that requires lots more power than the original Pontiac design consumed, there isn't a good reason to rip out a satisfactory design and replace it with a "one wire" alternator solution. Much of the claims for "one wire" as a superior system stem from inability to diagnose a broken charging system down to the component level. The "superiority" claims arise from the shotgun approach that replaces a modular charging system solution in place of component level repair. If you replace a charging system as a module, you are certain to correct most any charging issue without knowing which part is bad. Most problems stem from worn out brushes, or failure of the diode tree or regulator. All of these problems can be repaired cheaply without trashing the originality of one's classic car with a 2008 part.

One wire alternators also don't light the dash bulb when there is a charging problem. If one wants to "upgrade" to an internally regulated alternator, it would be better to install an alternator that lights the idiot lamp when there is a charging system failure. That is current design in cars today. It is readily installed in a firstgen if you understand the system, and the idiot lamp will still work. The one wire system without the warning lamp circuit is an aftermarket solution for elminiating wires. That is only important when the appearance of wiring is important.