I just report what Bill sang Dick, both on record and on the youtube video referenced above (though there he sings journey's over). As to changing it when you sing it, that's up to the singer; I do it all the time.

As regards the Pathetique's theme origin I checked up only on the reference above here (and in another thread I think) that it was derived from Piva Piva, which it doesn't seem to be. In the youtube video - from 2016 - Bill says that he "finally found out last year that the actual tune is an Italian folk tune". I haven't been able to verify even that.

Mick