mon, I'm sorry that Lily has to undergo surgery. I'm glad though that you like the new vet, trust is so important.
Did they give you any indication what kind of growth (benign vs malignant) Lily has?
Either way, I wish you and Lily the best of luck with the procedure!
PS, it's not that weird that one vet heard a heart murmur, and the other one didn't. Miss Kitty's emergency vet heard one, but her regular vet didn't, and I trust her more.