Predator 301cc 8hp stock timing

Would anyone know what the stock timing is on HF predator 8hp engines (hemi head). Can't find it anywhere online. Would it be the same as a gx270? 20degrees? The cam I'm running is a 275 which needs 28 degrees timing. The 6627 flywheel has no timing advance. I just want to make sure I'm running correct timing and don't have the equipment or know how to check it myself with a degree wheel. I read on nr racing site to run a 4 degree key, I see where some use a 6. Not sure if i need it at all.