Birth of a 1970 Dart Convertible

Here is the picture of the car that is going topless. I started cutting away at the conv. today I removed the right rear quarter panel trying to save it Dustin and myself didn't do too bad. Let me tell you there is a lot of a spot weld to remove to take it all apart. I think that I can take it all out in 1 piece but when the reinstall starts it will all have to come apart. I was just wondering anybody had any ideas how to measure the windshield frame before I remove it so when I install it to the same angle?