68 Fastback Glass Help

I have removed many old windshields without any breaks. Worst case scenario is if the glass was replaced in the past by someone who thought it would be a good idea to glue the glass into the channel of the gasket.
1. With a sharp, new blade cut all the way around the glass with the blade perpendicular to the glass' surface and just skimming along the edge of the glass. As long as you are careful, you'll be fine. Then, using soft but firm pressure from the inside, see if it will release. DO NOT PRY FROM THE OUTSIDE WITH ANY KIND OF TOOL. If it releases, even in just one spot, that's great. From the place it released work around with the blade, this time angling the cut so that you are cutting fresh rubber (the cutter blade will form an obtuse angle to the glass' surface. Then repeat with the pressure from the inside. If this does not work, see step 2.
2. It will be a pain, but repeat the cutting away of the original gasket on the inside (like you've already done on the outside.
3. I have never used one, bit there are tools with two handles and a ling piece of wire that are used to cut out windshields in modern cars where they are glued in.
4. With a very large hammer.... Just kidding. #1 has almost always worked for me, and if not, #2 should work.