I used to build engines with 600+ pounds of open valve force. Those had to be meticulously broken in, or you would flatten the cam in a matter of minutes. On our little stock Triumph engines, I can actually push the valves by hand, so they are very easy on cams.
My belief is that you didn't do anything wrong. For our stock springs to hurt your cam, either the cam or the lifters were not properly hardened. Especially if you got so many miles from it! Honestly, a break in problem manifests in minutes, and you get glitter in your oil from the metal that flies everywhere.
As for which cam to buy? A year ago I would say any of our "Big 3" suppliers. Unfortunately, this last week I have had a rash of really badly manufactured new parts from ALL of the suppliers. They all have their issues, and get batches of low quality parts, not necessarily their fault...but we all bear the brunt. I have never heard of a bad cam coming from Crower, Comp Cams, or Isky Cams. If you live in a big city, there are very good grinding services, that will do it right and makes sure the cam and lifters are properly faced and hardened.
On a note...since your cam has a bad lobe and there is doubt about it's hardness, I would not re-use it, even for a re-grind.