VERY Nice looking work ! I have done many race cars with the grounding setup such as yours, works fine.
The only issue to look out for is a potential difference between the electrical devices that are mounted to the chassis (motor loads) and the chassis components themselves. It is a mechanism for corrosion, can add to the other corrosion mechanisms that are inherent and unavoidable such as dissimilar metals in contact with each other, fuel by products, lubricants, etc.
As I said, works fine for a race car, not good for a street car loaded with a zillion other luxury devices and such invasive things as trim screw penetrations, coated fabrics, adhesives, etc.
I now use a hybrid version, I complete the "ground" system such as yours, but always tie to the chassis just for the corrosion possibility especially if there is a fortune in paint work... Maybe unnecessary, but better safe than sorry. I also use versicable (braided wire) anyplace there is high temp or even the remote possibility of chafing - the fiberglass jacket is almost impervious, but it does weigh a touch more...
Point being, it is often impossible not to include the chassis in the ground system somewhere along the line ( point I was trying to make). The key is "most direct path with least amount of connections" - benefit of a floating ground, especially when you have sensitive electronics that require precise current / voltage. I just finished my street rod project and also went with a "hybrid" ( for lack of a better term ) grounding system. Many of the components in my system resided in a fiberglass body, so from a practical side, it behooved me to use the frame as a grounding component in some instances. I also had no critically sensitive electronics on board. Pic shows two main + and - terminals located on the fire wall. One area that is often over looked in the grounding system is the radiator. If yours isn't grounded, it needs to be.
