If you running a MSD ignition , I been told that the dial back timing light will not be acurate . Just use a cheap one like a Sunpro . That is what I use for mine . Just have to use the balancer and make sure it is degreed or put a timing tape on it ..
I think MSD sell a timing light that works , but I can't afford one , so I just use my SunPro one and make a mark on my balancer for 36 degrees and time it that way . My distributor is also locked out ..
Hopefully one of the engine expert will chime in and give more advice
If I make it , I can bring one of each . But right now I am sick and do not want to do much at this time , Hoping to get better before Saturday