Hi, I happened on this searching the A500 here.
It's very rare by now, I'm afraid. There's one on sale on ebay atm but won't be for long, I'm sure.
The LED assembly, consider reconstructing its "glass" out of acrylic from a hobby shop, that should be doable and look ok from the outside.
In case you're new to electronics: The LEDs themselves are utterly generic parts, just the typical 5 mm LEDs you'll be able to order for a buck. You could chose your own colors 😉
Reset button: 3D printer job, any old push button behind that, some hot glue.
Really not worth gutting another case, why would you?
The "gutted front panel", sadly, that's a somewhat frequent phenomenon.
Idiots who want to sell the motherboard think the front panel cables belong to the mobo and so do the LEDs and buttons. So they ruin a 100 € AT tower for a 20 € motherboard...