From what I know, they originally made the chassis for his Sedan Delivery car and then kept making kits with Buttera's name on them and used the same chassis with different bodies. Thus they managed to make some of the worst street rod kits ever! Yes, everything is odd sized and smaller than scale!
I have them for the sake of nostalgia but I highly doubt I will build them again! But I can not really say that since I never managed to finish one when I was a kid!!
The Model T kits in this series ARE accurate, and are correct 1/25 scale. The '33 and '34 Fords that use the same chassis are undersized. The first car issued in the series was the '26 T sedan, the only one that actually exists as a 1:1 car. The kit was scaled right off of the actual car, a sedan built by John Buttera for his wife to drive. The body is pretty close to stock, but the fenders are widened a couple inches (Buttera jokingly called them "the rare Australian fenders").
The first issue of the sedan kit doesn't have any photos of the model, but instead had photos of the actual car. It didn't sell well until Revell changed the box to include photos of the assembled model. After that, modelers realized that the kit wasn't like earlier Revell kits (opening everything, tough to assemble) and sales took off. The '33 and '34 coupe kits are undersized, but the chassis is the same one that was included in the T kits. That makes those worth a look if you only need the chassis.