The bulbs in a traditional 6v 3w bottle generator bike lighting system are:

6v 3.0w 0.5a headlight only (or)

6v 2.4w 0.4a headlight
6v 0.6w 0.1a taillight

I want to replace bulbs with these three specs with suitable LEDs.
How do I determine which LEDs to use, and how do I match them to
the generator so they will work. I would like to generate as much light
as possible, but I realize that is a secondary goal. Which LEDs should
I purchase for each of these, and how do I match them to the generator
by the selective use of appropriate resistors?

Sources for the LEDs would also be appreciated.

Thanks much for your help.