Not exactly true.
You can purchase a maintenance free battery from "Antique Auto Battery" in Ohio that looks the part, and fits the top frame perfectly.
However, because it is a modern battery in a classic case the overall height is a problem, and it wont in our cars unless you lower the base tray. As I was doing a complete resto I decided to get that done.
I even went with the yellow caps to emulate John's (aka 49er) original engine bay photo.
For the fanatics I would suggest