I feel like the top of the window opening should line up height-wise with the top of the side window openings, which would place it somewhere in the middle of your two choices. Since the body line curves up so far in the back, having it the same height opening as the sides puts the hole too far up into the roof, looking odd. But too small makes it out of proportion to the rest of the already-big sedan body. You're wise in very carefully planning the size of the hole. It's a make-or-break type item.
Interesting. When I started reading it, I was thinking "of course it should be the same size as the side windows" Looking at the photos I'm not so sure. It appears that in the 10" version, the top of the window is higher then the top of the side windows. Probably because with the way the body line curves up in the back, the bottom of the window needs to move up, which moves the entire window up if the opening is the same size. What I would do is set the top of the rear window at the same height as the top of the side windows, and let the window be whatever size that turns out to be. Make sense?
I'm liking the lower example. Makes it appear chopped more. My buddy has a '48 Chevy sedan built by a well known builder that I always thought had a chopped top. The windshield only was shortened making it appear to be chopped.
Rear window should be chopped the same as the rest of the roof; otherwise it looks goofy in many cases. In response to your question, the 10" version looks like a picture window. IMO.
I like version 2 it's obvious to knowing observers that it is chopped but it doesn't have that mail slot look that seems to be all too popular. The final decision might depend on what the view through the rear view mirror is though. Too low of an opening in relation to the mirror doesn't let you see far enough behind you and from my experience you end up using the inside mirror a lot more than the little outside mirror.
I like the idea of lining the top of the window up with the side windows and then let the car tell you what it wants for the opening and bottom height
I like the second example also,looks like the rear window opening is centered on the side openings. IMO much more pleasing to the eye.
Kind of a slippery slope on the back window deal. Looking dead-on the back, there's no reference point, but quarter view there is. So, an inch or two can make or break it. I'm definitely in the 7-ish camp. I'd like to see what an inch either way looks like.
Version 2 looks best. Keep the top of the window for the side and back at the same elevation. The back window will be smaller because the bottom of window at the rear is higher than the sides.
gotta go 7 inch or smaller, Id fit the lower back panel to the body and start sizing it up from there, if the rest is chopped 4 inch you may not want to chop the back window quite as much as that. but I def think 10 inch would look way off on the back and just look goofy.
Here is what I got so far. The bottom section is lined up with the belt line, the top of the window is lined up exactly to the top of the side windows, this makes the opening 8".
This is seven inch,it's a sedan back window,it's in the middle of the side windows,but it's a bitch to see out of! The way you have it looks good!