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.

[Second Series]

That's interesting, I just watched a video about setting the timing with a test light. Right hand drive and sounded like an Australian talking. That looked like a carbed engine and probably a points distributor. I don't think that method will work with an electronic distributor. I'm not sure how that test goes, but I have used a test light on the power to the distributor and ground to adjust points. When the points are open there is 12v at the wire so the light comes on. If the points are working and they close, the 12v is grounded and the light goes off. Seems opposite of what was happening in the video. The 12v line is after the coil, so when the points close to ground the coil is energized.
When I replaced the distributor on my '88 TBI truck, I just put it close to where the old one was, the ECM adjusts for timing. I still need to check the timing with a light, but it does work close enough. Engine starts every time. Maybe you can have someone rotate the dist while cranking to get it done, I don't know maybe a bad idea?

[Accelo]

Early ORBI GM distributors required a timing light to set the timing.
.You had to unplug a wire to the computer so it didn't take control of the timing.
I believe the wire, that had to be unplugged, was behind the glove-box. Been a long time so I am guessing on this one.
A timing light is connected to the battery, one 12V+ and one 12v-.
Then the third wire attaches to the #1 plug with. The clamp is inductive. No actual connection to the high voltage.