Yep, I had a guy break THREE 55-59 (?) Chevy truck windshields for me before he called me! That was a $1000 lesson I won't soon forget.
VERY few glass shops can cut a curved windshield, VERY few.
One thing I can tell you for sure, DO NOT chop the top and finish it all off before you get the glass cut. You need to either make a fiberglass pattern from a windshield and cut it down to the top then use it for a pattern to cut the glass, OR, just have the glass cut first and simply chop the top to fit the glass. I highly recommend making the pattern from fiberglass first so you don't have to baby the cut glass while fitting the top to it.
Notice I said "fitting the top to the glass". Because that is EXACTLY what you do with a complex windshield like that.
Let me explain, the glass is impossible to modify other than cutting the edge off. You can't change the "shape" of the glass anyway you want, right? No, you can't, and you DO change the "shape" (but not how you want to) WHEN you cut it smaller. The outside edge of that glass will not only be shorter, it will be DIFFERENT than it was. Soooooooo the "hole" in the cab it goes into will not be the same as the glass once cut. On your truck the glass will be "laid back" when you cut it down. I am not talking about laying the glass back as opposed to lengthening the top "laying back". I am talking if you lengthen the top (and widen it as well will be needed on that particular cab) the windshield posts will go straight up and down just as before. HOWEVER, when you cut the glass down, remember the "shape" of the glass will change. Then you cut it down you have to lay the glass back slightly to make the top fit back to the cab. When you do this, the bottom corners need to be trimmed as well so it can lean back. When you do that the bottom corners on the back side will be moved forward in the "hole" on the cab and you will need to ADD metal to the cab to reach out to the windshield!
All of this is no big deal as long as you are ready for it. Make a fiberglass pattern and you will be MILES ahead.