Probably need to check your part against the full score or the rehearsal piano reduction to find out what’s going on before and after those glissandi so you’ll know what chord or key you’re sliding toward. That will help you choose the pedals settings you’ll need. Sometimes when they’re written in, they still don’t sound right with the rest of the orchestra and you have to make some judicious changes. If it’s convenient for you to sit in on a prior rehearsal, maybe you can get the info you need.
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