Nylon multi-filament core strings are rarely discussed here on TB, with a notable exception, the Thomastik-Infeld Acousticore phosphor bronze strings, with which Turner Renaissance basses come equipped.
Then, there's also some discussion on the Pyramid set for the Kala UBass (look for the megathread on the Basses subboard), made like the Hannabach contrabass sets (silver plated copper wound on nylon silk).
I also remembered and've just dug out a post
by a Spanish member who put Royal Classics contrabass strings on his ABG: they have a 6 string set but I couldn't find 4 string ones, other than a curious, contra-baritone uke (or "Chicago" tenor guitar) tuning (DGBE) one. bullT's bass itself is interesting: it appears that a number of Spanish and Portuguese makers offer ABGs in classical guitar form.
Some personal experience/relayed info/assorted ramblings from my past posts:
-Acousticores have lower priced competition by Pyramid and La Bella;
-so have Hannabach silver nylons - the aforementioned Royal Classics, Pyramid and La Bella, as well as Savarez
(stringsbymail.com sells them in the US for little coin, and also carry Hannabach and La Bella);
-I use Savs on my cheaparse mid-scale ABG, like them enough that I'm gonna buy them again when the current set wears out;
-I suggested Savarez or Magma Transpositor Bass Sound sets as silverwound nyloncore alternatives for sub-short scale basses like the Kala, and a TBer tried the former on a classical guitar, and even tuned it a fourth lower than intended, with good results. Gold Tone MicroBass Talk Sub-Short Scale Talk
&ff Best Acoustic bass strings for sound alba Mike Inez on Alice in Chains Unplugged
Tell us more about your project:
4? scaled-up classical
like the Arias?
biiig body like the Caldersmith
long scale, I presume?