La Bella Rectified Nylon .040, Single String

I have a few instruments with unconventional tunings; i.e. a modified tenor guitalele modified to have 5 strings tuned in fifths and a concert ukulele also tuned in fifths. I use the ukulele to play Bach pieces transcribed for Mandolin. I use the 5 string ukulele for mainly the Bach 6th Cello Suite which was originally written by Back for 5 string cello, but I also transcribe other pieces for guitar for playing on the instrument. Strings by Mail stocks a huge number of the La Bella strings both wound and unwound nylon. The work perfectly as planned as I have a computer program that calculates the string diameter given the type of string (wound, unwound, nylon, polycarbonate, etc.) length of the string and the desired tension. There is nowhere else I can go to choose the correct strings.