I'm not familar with the Bela Fleck tune but my daughter did just get a new dog that she named Bella so I'll take a stab at this question......
As any Roscoehead that's been around this forum long knows, I've always been a big fan of the Spanish cedar body Roscoe's. They have a nice phat low end with lots of warmth. I've owned 7 Spanish cedar Roscoe's with various tops, FB's and electronics and they all sounded good. But I'm not sure that I'd describe them as having a "tight round bottom with a clear top". Of course all of them had the Bart p/u's.
IMO if you added the Nord p/u's and an Aguilar OBP-3 (or maybe the Audere but I've yet to hear the Roscoe version) I think that you'd come closer a "tight round bottom with a clear top".
Also maybe add a nice maple top and maple FB to enhance the highs.
Of course my favorite Roscoe now is an ash body/maple top with a wenge wedge neck w/maple FB and the Nord p/u's w/Aggie OBP-3 pre. By far the clearest and most versatile sounding Roscoe that I've owned.
Man I love that bass!
Good luck!