Im currently using a Antigravity 4 cell with my bike. I use an aftermarket car regulator that I had to wire myself.
The problem is the older mechanical ones. The stock solid state regs are fine if they work. Its the newer technology batteries that cant take the variable charge rate.
With that said, I started using this 4 cell battery this year, so I have no idea how long it will last. I have a volt gauge on my bike and lately thats been giving me high voltage readings, like around 14.8 at all times no matter if I have every light on or not. The tail light is LED and acts as a runner, brake, and tag light. Im keeping an eye on the battery, its gotta be overloading and greatly reducing lifespan.. I do not know yet.
The regulator I use is the R292 from BWD, Borg Warner also makes the same one. I am not sure if it is compatible, or makes a difference if your bike came stock with a solid state reg. My 76 had a mechanical one so this was a nice upgrade for me.