One of the major parts of my project is taking on this exact endeavor.
The glass in the international was bad from day 1, and I still can't find even factory replacement glass for it.
As some have mentioned above, me, as a newby, got carried away with the cut off wheels and welder and chopped the top where I wanted it, before researching how the glass would need to get done.
Afterwords, once I started looking into it, and learned the monumental task I would need to complete, I decided the best way would be to split the windshield so that I would be working with two smaller pieces vs one giant big one.
I used the old glass and made a template mimicking the radius the old glass had. This small template allowed me to head to the junk yard to find what vehicles has matching radius.
I have it narrowed down to about 5 different cars.
Next step, which I'm not exactly looking forward to completing, is to price out each one, and buy a bunch of them, and try my hand at cutting.
My biggest fear is I mis match the support from the under side and get half way through and break the glass. To to combat that, I hope to build a frame, with that "big gap" spray foam stuff from the big box store and let it cure to the radius of the glass to provide a nice even support from the under side. At that point, I'll try cutting/blasting/sanding till I get one of the 40 windshields right I suppose