If you look under powertrain --> Engine, you can see the timing alignment and lash procedures: http://deneau.info/ls/
I looked up some random 2000 LS V8 on EBay and fed that VIN into fordparts.com. It looks like the shims are still available at $20/ea. they are all varying thickness, so you would want to mic the ones he has, install them, and then check the lash. If the valve lash is negative, then measure the height of the shim to the spring seat without the cam on, and then try to measure it with the cam on. The difference is now negative the lash is, so reduce the shim size at least that much. If you can't measure it with the cam on, then use a straight edge laid across a machined flat part of the head and measure the difference in height from it to the valve shim instead. Hope you got a trust-worthy set of micrometers. If you are LUCKY, the new valve will be within spec.
