Macduf the answer is yes on the lever BUT not a direct fit. I have done this with a 1/2 ratchet.
The lever itself yes, but only when I shaved the under side of the lever down. It has to clear that lip on the ratchet body, and the Proto lever would be too firm and too short to bend. The cam that the lever peens onto cannot be interchanged to my knowledge as there is a step down in one of them.
I tried thinking it was a direct fit once.