Hard Parts

[gbaker@customcpu.com (Baker, G.)]

All,
  When it comes to valves, guides and other tolerance related parts where is
the best
source?  I know custom pistons are about as cheap and mostly better than
Moss or other
ordered ones but what about valves, guides and train parts?  Are there
custom valve,
guide makers and how do they stack up?  If so what are there names.
Thanks in advance,
Gregg Baker