Setting base timing using a test light on TBI 350?

[Fruitloop]

Okay guys so I'm stuck at work stranded here I don't have a test light I've already replaced the head gaskets in my truck I stopped the distributor and without the timing light I have no way to tell exactly where a zero is. So I got on YouTube found a video on how to do it without a timing light and the guy used the test light but it wasn't on my specific motor and the video was horrible and you couldn't even hear the guy so I don't even know where to hook the test light to but I do know that the ignition has to be on you have to ground the test light I just don't know where to probe for the 12 volts to light up the test light. I thought it was the tach wire but everyone keeps telling me the tag wire is negative so how do I make the test light light up directly at zero degrees when I turn the distributor? Because if I probe the number one spark plug wire I think it's probably going to blow my test light out considering it's a coil and I'm pretty sure it sends way more than 12 volts to a spark plug don't know if I'm wrong or right but I only have one test light so if I blow it I'm ****ed.
I'm hoping somebody chimes in really quick so I can get my ass back to work cuz I've been ****ing with this thing for 3 days now trying to get it started and even though I found top dead center on the compression stroke I still couldn't get the thing started but I have fuel and I had spark and it tried to start it just wouldn't start.