I think that makes a lot of sense. That battery-to-body ground connection is far from optimal. Carrying that high current through the thin body metal, then hoping it finds its way to the frame and ultimately the block, isn't the best practice.
When I restored my TR4A, I ran the battery negative cable directly to the engine block, then I have a 3/8" braided cable from the block to the frame. I wanted to run a similar cable from the frame to the body, but there was no good connection point on the body. Instead, I ran a #12 wire from the battery connection to the body at the battery's previous connection point. I think that covers all the bases.