Door won't latch on my '62 Valiant

You are going to need an impact driver to tighten the screws on the latch after you adjust it. You can't get them tight enough with a regular screw driver to keep them from moving. I adjusted the latches on my '66 Valiant and didn't use one. The doors worked fine for a while and then I hit a pot hole and it turned into a 3 door when the latch moved. Never did get that door open but the other 3 got the impact treatment and are fine to this day.