Thank you for the measurements.
Unless you're willing to perform surgery to the B and possibly E strings (unravel them to length, then solder or otherwise - superglue, heat-shrink tubing - secure them where the unravelling stops), you have two courses of action:
1) get a MEDIUM-scale (usually 34" ball to taper) 5-string set and hope they clear the nut (in order to gain a fraction of an inch, you could remove the ball-end - takes some filing of its side to slip it off the loop of string core - have the loop pass through the tailpiece hole, then put a short piece of metal through the loop so that it stays there):
-
Warwick makes this
roundwound, stainless-steel set, the
Black Label 39300 ML 5 (40-60-80-100-130)
[Invalid or Expired Link Removed]
and at least another one, the
39301 ML 5 (45-65-85-105-135);
- as for
flatwounds,
Dunlop makes two sets, the
DBFS40120M (40-60-80-100-120)
https://www.amazon.com/Dunlop-Flatwound-Medium-Strings-DBFS40120M/dp/B079X3S3DZ
and the
DBFS45125M (45-65-85-105-125); for your high C, you'll need to either keep the old "high" B of the bass VI and move it up one slot, or source a single high C (it may reach the tuning post with the bare core, but tying it is doable)
2) get a LONG-scale 6-string set of your choice, and thread the B and the E strings through pieces of stiff tubing so that, after installation, said tubing separates the ball end from the tailpiece and, at the other side, the string correctly tapers between nut and post. The needed length of the tubing for the B should be between .5" and 3.5", methinks, depending on the length of the string; for the E you'll need less (.5" to 1.5" will probably do).