These older lights can still be useful, as task lights and limited duty. Incandescent can be nice in cooler climates (illuminates and hand-warms). But I'd not bother upgrading your A2. You love the light, so keep it as a nostalgic piece. Fire it up on occasion. And if it's in top physical condition, that's a bonus.
There is something about having a very solidly built host. Surefire still does that extremely well, but for a hefty price. Some models lend themselves more to modding than others. I picked up a KROMA recently. And yes, it's quite dim in comparison to other lights I own, of smaller size. I bought an Astrolux S43S for 1/3rd the price and it's an entirely different class of functionality. But the Kroma has a weird, unusual design and feels so tremendously solid. While I'd been using my old NovaTac 120P in moonlight mode for short tasks late at night, I'm now enjoying use of the red illumination (easier on the eyes, so it has less impact on a sleepy mind). I'd been tempted to modify it, having a more powerful and Hi-CRI emitter installed, but now I'm feeling like it would be better off kept as stock.