I second the high 40% crit chance. Or at least as close to 40% as you can get it. I would suggest having a crit rating just over 300.
I am frequently told by perfectly good players, who have never played an operative mind you, that 34% crit chance is enough. I believe this would be plenty for a sorc healer. I see sorc healers and operative healers having miles of differences between them.
Operatives have to work with long cast times until their tactical advantage is up. We also crit differently from sorcs. For these reasons, I would actually suggest having a decent amount of both crit and alacrity. Each about 300, THEN worry about power and surge. I currently have 315 alacrity and a 1.73s casting time on kolto injection, which is still slightly high to me. Let me explain why: Since kolto infusion takes a stack of tac away, I use it less in order to keep my tac up and keep tac-requiring skills unlocked. Therefore, if I'm looking for a big heal, I resort to Kolto Injection, unless I need speed, in which case I do resort to Infusion. So...if your alacrity is low and you aren't critting often and someone requires a big heal, you won't be delivering a good enough heal if it takes 2 seconds to cast and then doesn't even crit.