You would be amazed what a simple red or black sharpie dot on the lower edge of the dizzy where it sits on the block and then one on the block. A sharpie mark can last for several years.
No need to overthink the simple for no more then your doing.
Have a black dot on your dizzy, match it to a black dot on your block for na, and a red dot for spray. Check one time a year with a timing light for chain stretch.
That is what I'm doing now and have done for quite a while. Not a problem for one or two points but with multiple different settings for different N2O jettings, was thinking I could do it better...
