Are you comfortable soldering resistors to LED legs, adding heat-shrink tubing, etc.?
You can attach the Evans 9-18V LEDs assemblies to a PS2 headlight wires (or any PS2 incandescent output for that matter) but it will likely be too dim. That's because the PS2 output puts out effectively only 6V DC. It can be hooked in either orientation/polarity since Evans accepts AC so the PS2 DC will work.
Try it. You can splice it into the factory headlight so both go on/off together. If LED is too dim, then you need to lower the resistor value in the Evans harness but this is likely difficult to do. Instead, you need to get a bare LED and solder a resistor and connect to the PS2 output wires. So you'd be buying a red LED for rear, green LED for front, and white LED for headlight. GRJ or one of the guys knows the resistor value as this modification has been made by many guys.
The green LEDs GRJ shows are really nice but somewhat spendy. But they are small enough to directly install. I like your fiber approach because you can get 1mm, 1.5mm, 2mm, etc. fiber and share a single LED to drive a pair of marker, classification lights. The more common LED sizes of 3mm or 5mm diameter are only, say, 10 cents on eBay. Resistors are a few pennies each.
