At 1:30 to the end that is FOR SURE Oscar Rocchi possibly from Ring library, late 70's. It sounds identical to his tune "Ambra", same exact chords, same ambience, same instrumentation, but the piano melody is ever so slightly different. So it could be some take on that tune. Or maybe it is that tune but the hip hop people chopped it up to play a different piano melody. But no doubt, it's Oscar.
Here's the tune i'm talkin about (first cut on this full album Youtube post)
Indeed, the sample you have attached does have striking similarities, however, it is not the same sample. The chord sequences used in this song are very common, there is nothing unusual about them, and therefore, they can be found in thousands of other songs. The rhythmic-melodic pattern of the bass is very different, in the sample I proposed, it is more mobile and active, and still has a different melodic movement. I am convinced that hip-hopers did not alter the original melody in any way, since it is unchanged and the same in all disparate samples, and it is unlikely that people unrelated to each other could get the same melody through changes. bearing in mind all these circumstances, I can safely conclude that the melody of the original did not change in any way. The general conclusion: it's really similar, but still not the same.