For the bridge of a song, I quote 7 non-contiguous bars ( 3 & 4) from a 16 bar chorus I didn’t write. Although I plan to cite my source, I changed the original melody by cutting 9 bars from the middle of a 16-bar phrase. My recording is 106 bars long. The 3- & 4-bar quotes together are roughly 6% of the new work. What kind of copyright do I need? There are other factors: The source song is over 70 years old. Both authors are deceased.