As I said, it's either
1) one of those three I listed earlier, or
2) you must be willing to mod the bridge.
- The La Bella MBLS (aka MBSLS on the eBay) are about 28" ball to silk, or ball to taper (in your case the difference may not be trivial); I expect them to be quite stiff, and require a non trivial amount of saddle relocation.
[They make another set of identical (49-69-89-109) for Kala, the KA-BASS-4FW-SC (last suffix important to distinguish them from the Galli-made nyloncore set), but the instrument they make them for (Kala Solid Body U•Bass) looks to have not more than 25.5" from ball to E-string tuner.
Ditto for the Dogal flats made for the Tiny Boy Bass: they look like they'd be, er, too short for Cort.]
- Pyramid is usually available for custom work;
- so is, possibly, a manufacturer from Argentina, Lemma Sound, I've recently become aware of;
- unless you file the slot wider, you said a 090 can go in there. I guess you could try to jury-rig long-scale flats in there.
Same caveat applies: in all likelihood, all of the above would intonate sharp, with the bridge left stock.