also never reuse an exhaust valve bc they are always the first to fail and thoroughly check any old intake valves i.e head diameter, overall length, stem diameter, margin, and face angle. Tolereances are very tight...Out spec worn valves will lead to future dispair and major expensive repair when that valve you reused but shouldn't have breaks off and goes through the piston top. When you put that old valve on the drill and sanded it you decreased its diameter if it was already decreased from engine wear you just made it worse! vw specs say you can reuse a valve worn up to .003" but .001" is the max I would use... worn stems out of tolerance will cause the motor to burn oil, you will also loose compression, have poorer fuel milage, decreased horsepower and last but not least premature wear on the valve stems and those nice new guides you just installed. Cylinder head work is the most important part of the engine especially on the older ones where you want as much get up and go as possible especially when you are trying to get on the highway and the car you're driving has 25 or 36 hp lol. Hope that head was not for a customer. Tom Wilson's book "how to rebuild your vw motor" is essential reading.