An easier way to take the valves out are to use a rag, place it inside of the combustion chamber use a socket & a hammer & tap on the socket, the keepers will pop right out usually w/a couple of hits. This probably cant be done with supper stiff springs, unless you have a bigger hammer.
When the valve tips are mushroomed, you would use a smooth cut file & file the top side of the tips down, this way, it won't damage the guides.
Did
you oil/grease up the main bearings while you was trying to turn the crank?
