Airplane mishaps are not fun. Glad you put it down safely!
Any idea why the valvesprings broke? How many hours on them? Did you send them off for analysis? I wonder if there was impurities in the raw spring steel which served as stress risers. Could really out of whack lash have beat them to death? Having a multiple simultaneous failure would make me very nervous, hope you changed all the valvesprings and found the real problem.
I've had a fun IFE experience too. A couple years back a friend and I had the great idea of going flying in a rental 152 when it was 110F out (mind you, no A/C other than the windows and fresh air popouts at the top of the windscreen...) Preflight went OK, taxied out and took off. About 800 feet up while still climbing we got to watch the oil temp gauge start making a dash for the red zone-- and it kept on going. The engine didn't seem to be down on power and because of the speed the gauge went to the redline we suspected an electrical malfunction but decided to play it safe. By the time we got it turned around and on final it wasn't running all that great and you could sure smell it was baked. Definately not a gauge problem.
Never heard back from the rental outfit what happened, just glad we got it to the ground on our terms-- not its terms. Didn't really want to land short and stick it in the cornfield, although it would have made for a better story.