I replaced my windshield about a year ago. I don't recall how the old one fit this car. Seems it was better than this. At that time I also replaced the original trim with rubber trim. Maybe the original trim covered or hid a bad fit better? With this ~1/2" gap the rubber has a hard time staying in place. The gap on the other side is equal, little smaller on the top. The curvature is a bit excessive on the top passenger side, more so than the drivers side. I thought the Chinese glass was flatter than original.
Not knowing the history of this car, I don't know if the windshield is %100 the problem.
There are indications that the quarter panels were replaced with welds visible at the bottom of the A pillars. The body dimensions are reasonable.
I need to get this resolved before paint.
Any body work guys run into this before? Bad glass?

Placement of the windshield during install is more critical with the rubber. It must be centered with same gap all the way around.

As above, spacing when fitting is vital for an even fit. As it's in you can measure corner to corner diagonally to see if the apperture is square or not. The answer to that will get you closer to the end answer.

A large gap like that is how the car was designed. There are small black clips around the outside edge that hold the stock trim in place. There needs to be room for those clips, and there needs to be room for those clips to move towards the glass as the trim is being snapped into place.

Some glass mfg is a little bigger, some is a little smaller, but I've never seen one that was too small (for the stock trim). Also, welding or accidents won't affect that gap.

If you are going OME McMark is correct. If you are replacing with the rubber. No clips and center.

The glass is centered to a best fit condition. Top and bottom are equal 7 mm gap all the way across.
Passenger side, vertically is 11 mm at bottom, 10 mm at top.
Drivers side is 11 mm at bottom 6 mm at top.

I would love to split the top sides 8.5 mm equal but that would give me a 13.5 mm gap at the bottom drivers side.

McMark, this is not a problem for the OEM trim but the rubber trim is at its limit and a constant 7~8 mm gap on the corners sure would help retain the rubber in location.
I do think that the excessive curvature on the top passenger side glass might would be a problem with the OEM trim.

JFG I agree with the diagonal corner to corner check that is about the only one I haven't checked.
Sure wish I kept the old glass, hopping I ended up with a bogus Chinese glass.

But this whole thing is about how the non-stock rubber trim fits. You seem to be concerned that the rubber trim doesn't fit well. But it's not stock, so how is 'bogus Chinese glass' the issue? It's made for a 914 and it fits a 914 and works with 914 window trim. If you wanna customize your car with non-stock rubber surround, you have the obligation to use something that works how you want it to. It's not the glass mfg job to fit your unique application. There are lots of rubber trim profiles available. Maybe you just need to try and find an alternate supplier? Find something wider and all the problems are solved, right?

That's what i did on mine, found some rubber trim that was wide enough for the gap.

Also, don't try to bend the rubber around the bottom corners, it will not stay flat.
I cut the trim into 2 pieces, one going straight across the bottom, the other going up the sides and along the top.

The top of the drivers side window frame is bend. Happens all the time, people use that corner to lift themselves out of the car, bending it in the process.

You can easily square the frame before installing the window by bending it up again, all you need is a bit of elbow grease.

Square the top of the windshield frame against the targa bar (x pattern) ...