Quality 5mm high brightness LEDs can be sourced from Nichia, Cree, Kingbright, etc.
Check out this BuckToot LED driver. It has a wide operating range, but it has more than enough power for your needs. I use these for m projects. It's non dimmable, so it'll try its best to regulate down to low voltages, which can help with engine starts:
https://www.sparkfun.com/products/9642
7027-D-350 BuckToot LED Driver - LED Supply.com