How to decide when to change gears in a 86 mustang?

I have a 86 mustang with a 5.0 302 carburetor engine in it, Headers, Msd ignition set up, nothing major. Now, my rpm gauge stopped working and i'm going to get a tach with a shift light in it, and i was wondering for racing it on the track what rpm should i shift on so that i can set the tach up right? Thanks in advance...How to decide when to change gears in a 86 mustang?
There is no predetermined RPM to shift at. Everyone's car is different. Only you can determine your car's sweet spot in the RPM range and get the tach light pill you need from a speed shop that sells performance parts. If you don't intend on making any major changes in the way the car is set up right now and can feel wherever the power drops off in the upper RPMs then you don't need a Monster Tach. You play by ear. Huge tachs in a street and/or daily driven car are also an invitation to thieves to break into your ride once they see it.How to decide when to change gears in a 86 mustang?
if its a roller cam than you can shift it at 6,000 no problem but if its a flat bottom lifter than I would shift it at 5,500.
Find out where peak HP is, probably 5000rpm, that's where you shift.