When chopping a A sedan. I want to keep the swinging windshield. So I thought of cutting below the stud. But after looking I am wondering if there will be enough post below left to get the tapers lined up? I know I have to do some slicing. Does it matter where I cut, it's my first and I don't want to screw it up.
No help on where to cut, but I will add that from your avatar, it looks like you already have a Model A, so you already know just what a pain it is to see stop lights. From the tape on the project car, it looks like you're planning a 3" plus chop. So my suggestion is that any amount you can lean those "A" pillars back and NOT make it a noticeable lean back will improve your line of sight to stop lights. Don't lean them back too far that its noticeable, or itll look weird, but any amount of lean back would definitely help. Either that, or get used to hunching over and looking through your steering wheel just to see the stop lights. Also, those visors with the dimple die holes can also help see stop lights. My un-chopped Model A for inspiration:
Ive chopped quite a few 30s cars all different ways but specifically I cut my 30 coupe below the stud. That was a 5"chop. If I remember correctly it was just a verticle cut with a cutting wheel that reconciled the difference in taper. So your making a cross or t at the seam of the chop. Open the cut up a bit above the seam, close the cut up a bit below the seam. Easy peasy. Dont over think it. Dont lean the pillars it looks absolutely horrible on a model A. Seriously. Horrible. A sedan needs a 5" chop minimum.