Then if the cam profile is symetrical (which I doubt) one could go 8* advanced.
I don't think I'll ever go that far. May be limited to the offset woodruff keys available and the present chain stretch. I'm thinking there will be a big gap in available advance keys vs moving the gear one tooth and using the a key to retard. How many teeth on the cam gear?
Turning by hand is a given... even then, it can be close cold but things could touch when warm.

My plan is to check the current timing and log some mileage, performance figures now. Then document any change(s) made.

I think the in town drivability could be improved a bit by advancing the valve timing which would move the torque curve down closer to off idle rpm.