Is this a car you drive alot?? As in rainy weather or does it just come out on nice days? If it is a sunny day driver you might want to price a new WS before you start.. Not trying to jinx you but its just glass..
If you want to water proof it you really need to remove it and clean the pinchweld, reprime with 3M primer ( used with the butyl tape) and reset the windsheild... This is if you have no rust or damage in the pinchweld area..
Coming from an old glass guy you can never be sure you can get your old WS out without breaking it... The best way is with the piano wire type of cutter... The "L" shaped knife is much more apt to nick an edge and cause a crack...
I "think" the bottom of that WS might be hard to get at the sealant like some fords were of that era... If so cut the sealant at the top, both sides and VERY CAREFULLY push out on the windsheild while using a "banana knife" ( that is what the tool used to be called a LONG time ago) then while CAREFULLY pushing the glass out from the top, score the old tape at the bottom with the banana knife from the inside of the car.. Remember this is only if you cannot get to the sealant from the outside bottom.... Make sure the setting blocks at the bottom of the glass are in good shape before pushing and before you reset the WS, you might want to replace them if not... The weak point of glass is the edge. Once you nick the edge, apply pressure, or pry on the edge of the WS, you will probably be all done for the day.. Hope this helps...
Most of the glass removal tools are designed to remove a broken windshield so be real careful and do not get in a hurry...
