I am trying to recall the title of a novel. It is probably from the 80s (maybe as early as 70s,) in English, USA paperback.
I am pretty sure the cover had a piano keyboard wrapped around a person so he could easily play it. Like 360, or maybe in infinity shape. Not straight, it was curved.
Similar to this:
The MC gets hold of a time machine. I am not sure if he nvented it, inherited it, stole it, or found it.
I think he installed it in his van.
Main plot point: He went back in time and rescued a dying classical musician. Not Bach or Beethoven, but someone a little less well known. (Shubert or Liszt or someone like that.) He was dying of an STD and only had a few days(?) to live, before the MC 'rescued' him, brought him back to the future and cured it. The MC gave him modern instruments/equipment and let him compose. The MC might have then passed the composer's new work off as his own.
I have vague recollections of a title something like "The xxxxxxx Time Machine" but my GoogleFoo is poor and I am not finding anything.