I replaced the windshield in my 80 a little over a year ago and ended up using the more readily available, and I assume made by a Chinese company, glass option. It did leak a little between the gasket and the glass after initial install but I bought a tube of the 3m sealant and was able to address the leak without much effort and have seen no leaks sense. The leak happened in spite of my telling both the glass shop owner and the installer that the sealant was needed inside and out of the gasket, and showing them the FSM pages, etc. They did apply sealant inside and out (I was watching) but went a little light (or rubbed it off) in two spots which lead to small leaks.
Unless the "cheap Chinese glass" you have, or buy, is noticeably distorted then I'd say that the leak is down to install and not the glass. Even if the glass is a little off, which may be most evident in the corners, if the gasket has decent overlap with the body and is sealed properly it's shouldn't leak. As you probably know these windshields need adequate sealant/adhesive both between the glass and the rubber seal and the rubber seal and the body. If your windshield follows your body lines pretty well then the most practical option is likely to order a new OE windshield gasket and then find an installer that will remove and replace that gasket while also properly following the correct process for applying sealant.
If you have the patience to nail down exactly where the windshield is leaking and if the rubber gasket is in good shape you may be able to add more sealant like I did, to resolve the leaks. In my case I did this quickly after the initial install and knew that all was clean but if yours has been in for a long time it may not be possible to seal the leaks due to the curing of the sealant and the crud that is likely in the gaps. I was able to nail down the leak source and fix it, and I ended up adding more sealant wherever there seemed to be a deficit (on glass and body sides of gasket) just in case. Here's the sealant I used though I don't know if it's your best option or not:
I had to heat that sealant before use and run it through a pretty strong gun as it's very thick. My tube may have been a little old or that may just be the nature of this version of the stuff. I used a plastic trim tool to run around the seam between gasket and glass and then gasket and body to find any sections that weren't fully glued down and then I injected the sealant into those spaces. Denatured alcohol cuts the 3M sealant pretty well if it is uncured but it's messy stuff to work with if you go to excess. Basically, if the gasket is adhered properly it will be difficult to pry the gasket up from the glass or the body. If the gasket can be pried up so that the tool slips in then that's an area to clean out and fill completely with sealant. The issue with an older install will likely be avoiding leaks at the seams between the old sealant and new which is why going with a new gasket/install may be easier.
I share the above repair process because it may end up being helpful even if you do a full replacement with new glass, etc. Many folks have the leaky windshield issue due to installer mistake and will have the glass reinstalled until it's fixed but that's not always practical. I preferred to just address the problem myself rather than keep trying to get someone else to do it right. It's far better to just have the proper install from the get go for a number of reasons and it's worth focusing your efforts there if you think it's an achievable option.
Good luck, and whatever route you go be sure to test the windshield for leaks very carefully after the work is done. Directing a full stream from the water hose at both the glass and body side seams of the gasket from a variety of angles should show you if you have any leaks. The water droplets, or stream, can be hard to see and will likely not show up adjacent to the source of the leak. Often the water will run down the gasket to the lower corner area before then running into the interior of the 80.
