The crimp in that tube is normal. It was done to divert more oil to the rocker arms.
Once you get the new rod installed I would remove all the plugs and try to turn the engine by hand at the flywheel before starting. You'll know right away if a valve is stuck.
When you have the rocker assembly removed you can pull the push rods up and check to see if they're bent. They normally bend if a valve gets stuck closed. Keep the rods in order - put the same one back in from where you pulled it out.
You can search "+stuck +valve" on this forum and you'll see others remedies. They usually involve penetrating oil, or giving the valve a whack with a hammer, cushioned with a piece of wood.
