I’m blind in one eye and can’t see out of the other. Lol. Look for timing strap/mark on the electrode. Needs to be in the rounded arch of the electrode. Best place to start to be safe. Set total timing to say 34-35 deg tdc. If your running 100hp jets. Rule of thumb. Retard it 2 degrees per 50 hp. So in your case 4 degrees. Once you get a wideband. You can’t get it s little easier.
First thing. Make sure plugs are tapped correctly. And in the right heat range. Go a step or two colder. Warm up your engine with your normal plugs. Once up to Operating temperature in for those plugs out and put in your nitrous plate then do one hit turn the engine off as soon as you can after the first hit and check plugs . A lot of the time although consistent it won’t run the exact same every time. Firm is the retard your timing 2° for every 50 hp ..100 Hp. retarded 4° Set your total Tammy to 34 or 35° before top dead center at about 2425 2600 RPM that way all of your timing is in check the electrode strap after the first run you should see a tiny mark a thin little strap that goes across the electrode try to set your timing to where the mark strap is in the middle If the 90 degree bend. Take a few detailed pictures of plugs from a few different angles. Need to see down in the plug for fueling Rich or lean conditions . Set you plug gap to 35.