Double Bass How do I convert a BSX 5 String EUB Low B to a High C?

Should I just move the existing strings and get a C for the top? This is a slab bass so I don't think string sound is as big an issue but I'm an DB guy and it seems BG guys are fussy about strings so maybe it does matter and I should get a new set?
thanks
btw this is the bass
 
You can, but finding a high C that fits in well tension and soundwise is not easy. Often the high C strings have either more or a lot less tension.
Also steel core high Cs are rather thin and might be hard to press down to the fingerboard if they cut into the finger.
You might want to use synthetic core strings for the EUB, I was told downtuned Evah Solos with a regular Evah high C matches well, but I haven't had that in my hands or on my measuring bench.
Obligatos might work too (all regular, no Solos), but they might be a bit thick for your nut and bridge grooves. The Evahs might fit in better.
It might not be easy to find a high C string that fits into your expectations ...
 
You might ask D'Addario, they plan to make high Cs for their string sets, some might be ready but not officially announced. Otherwise a Spirocore 4/4 Mittel high C might do the job. It's just a bit thin like all steel core high Cs. But might work with less tension on the shorter scale.