Cool. How much does Wayne charge to bore out the tailcap?
As far as other power options go, you could use a 18650 Li-Ion cell. Lengthwise, you'd need a dummy C-cell. And you would need something to place around the 18650 to make up the diameter difference. I've used a multiple wrapping of cardboard. Durable? No. Cost effective? Yes. I've modded both my Blaster 1R's this way.
Another alternative is that two 14670 Li-Ion cells will fit side-by-side perfectly in a D tube. Wire them in parallel to get 3000mah capacity.
WARNING! - If you don't have any experince working with Li-Ion cells, forget this suggestion. They must be used within strict gudelines to avoid seroius damage. I know Wayne does not care for them at all. But you did ask for alternative power sources, and I have made many Li-Ion mods without incident.
