Overdriving a Lux3 UX1K ?? Direct Drive Options ?

I built another 2C mag mod, it was going to use a DB917 running a UX1K on 3xCR123. I got a bad DB converter that doesn't work so I just went ahead and put it together for direct drive. Since the emitter works best in the 3.7v range, running it on 2xC cells is a little dim. I guess I could run one 17670 or something with a longer spring.

Any ideas as to how much current is safe to run through a UX1K emitter in direct drive ? Any battery configurations I'm not thinking of that might work well ? I'm thinking three alkalines would work well, but not sure I can do that in a 2C mag body.

one of those 18650 or whatever and a resistor if needed. On a fresh charge it might overdrive some. I'd keep current ~1amp and not much over. Measure with a fresh charge and a couple ohms of resistance, and adjust resistance from there until you get what you want.

I just grabbed a chunk of rubber hose for a spacer and put a protected 17670 in it. I just stretched the spring out really long to fit and it's nice and bright now, although I don't think its so bright that it will damage the emitter. It appears to have similar output as my 27LT on high, with a tighter, brighter hotspot and more throw.

Open to other ideas though as far as cell selection for this light.