Hi All, I've been a bit slack in recent years and have a lot of "i must do that" to add to this forum. Anyway having said that I've got into my parts store and have finally got to posting these differences
The early sandcast brake pedal is a different design to the later sandcast brake pedal. I'm not sure of the exact VIN numbers where the change occurred but in conversation with a friend in Japan, would seem the pedal changed around VIN 3000.
The early brake pedal has a straight edge on the underside casting and is more prominent than the later one whereas the later pedal has a less prominent pointed casting. On the upper and lower side clamp end, the early pedal has casting ridges from the clamp bolt hole to where the arm is welded to the clamp. Later pedals don't have these cast ridges. Final difference is where the bend in the pedal occurs The early pedal has a bend slightly further forward from the mount to the later pedal.
As an aside I started collecting these pedals some years ago and was lucky enough to snap up a NOS one off eBay. The early one in the photo is that same NOS pedal.