Duster windshield removal/replacement

I have a leak in my 1971 Duster - I’ve had it for many years and it is coming from the windshield on the left and right edges. I had a new windshield installed over 10 years ago by a local glass shop and it leaked after a year or two. I’m assuming they didn’t use the correct “stuff” around the windshield. I talked to a local restoration shop about pulling the windshield and re-installing with the proper sealants. They said the risk of breaking the windshield was too much for they to attempt the job. Is this a reasonable assumption? I just checked and it looks like I can replace a broken windshield for less than $500 - so maybe I’m willing to take that chance. Questions are as follows:
1) What is the correct sealant for the installer to use if the windshield is removed and re-installed or replaced?
2) What’s the chance that a good shop could apply sealant to the existing windshield and stop the existing leaks?