I called JP in Australia today and spoke with Stan in their machine shop. He told me the JP 5619 single roller and JP5620 double roller was designed for the Holden VR-VT non supercharged engine and not any US engines.
According to him the timing would be off installing it straight up on a s/c V6.
I mentioned what their website showed for a Pontiac and he said they need to change it to say excluding supercharged.

We already know that Rollmaster is the same way.