Went scratchin' around for you a bit and found out that John Weston is a Delta blues musician, born 1927 in Arkansas and still lives there. The good news is, I found a couple of sites with info on his history: Click here

and a place where you can buy his 3 CD's if you're interested: Click here

But that bad news is, on the second site, if you click on the "More Info" section, the cuts on the CD's are listed and Highway 51 doesn't appear on any of them. I also checked out some Curtis Jones (1906) sites but found no hint that Weston ever recorded the song...maybe it was an obscure live performance tape you heard?? Anyway, maybe these sites will be helpful anyway.