The easiest mod is the addition of a Welch Allyn 1160 bulb, which effectively doubles the output. It shortens runtime, but thats the tradeoff.
Then you can scrap the standard pack, add NiMH cells, and run the 1160 for essentially the same amount of time as a the stock bulb/pack combo.
Or you can add a FiveMega adaptor, run 9 high current AA's (the stock charger can be modded to charge this pack) and run a WelchAllyn 1185. This raises the bulb lumens to around 1200 versus the stock 200 or so.
The stock reflector is fine with these mods, but if you want to smooth it out, a custom cut Carley orange peel reflector can be had.
That should get you started!!
Bill