At the second link I spotted no 3 mm UV LEDs, but at the first site they have 3 mm ones WUV303-C395-C(395±5nm) , WUV303-C405(405±5nm).

IIRC, the supply voltage is 5V, so the 3.7V they sport should be OK. You might want a different resistor value than supplied (IIRC 1kOhm) in the resistor pack. I'd get the LEDs, hook one up with wires and trim potentionemeter, and trim until you had the output you wanted with the knobs you're using. Then measure what the pot says and get the closest available resistor pack...

But for the knob you need SMD LEDs, which the second site has (the first hints that all their LEDs aren't in their catalog, so you might want to ask them about SMD LEDs as well).
E1S09-OPOAP-02, 385 nm, 1.7 mW @ 20 mA, SMD, 3.0 x 3.4 mm², 110° viewing angle
looks to be the best match.

/Michael