You may want to replace sunfire cape, seeing that it gives bad stats for its passive. Then again, what is 35/sec if you can't always be next to the enemy?

Dodge masteries are not so good on Amumu. After all, his main damage source all the way to early part of late game is tantrum, which is faster when you get hit. Same for runes.

Good hands > Persevereance
You have to be alive at MOST times, and your 4% increase in regen isn't that good, if you do some calculations. Also note that fights are usually fast, so regen is pretty much useless then.

Hope it helps :)