I have a few 805 LR boards, and the website says it can take up to a 1 Gig Duron or Athlon...
But I want to put a 1.4 Athlon in it.
Is there any way to do that?
Depends on which revision it is. Early ones have VIA KT133 chipset, no 133 MHz CPU bus there. You need a 1400/100 Athlon in those. The later ones had KT133A, capable of running 1400/133 as well.