Ok, I like the sound of the SD-1... it's a great cheap o/d

but my soldering iron is gathering dust - so i want to mod it.... I've bought all the components, except for 1..... A new on/off LED

My electronics knowledge is a bit thin, so I'm not sure what voltage LED to buy, or what resistor to put in front of it

Here's an SD-1 Schematic could somebody please help me figure out what voltage/current Super-bright LED to put in it - or if i need to - what resistor to put in.
It's already got a current limiting resistor (the 3.9K) Pretty much any LED should work.