Good DIY mod for oringinal 8xAA 800 Lumen TK41?

Just got a FW4A, and it makes my old TK41 feel really big and heavy for what it does. It looks like it has decent cooling, and a good throw reflector, so thought maybe it could be updated pretty easily with a new emitter. Asked a couple custom builders about mods but they said it wouldn’t be worth it. Any recommendations on something I might be able to do myself to get more output?