Do the HCI first.
Couple reasons, first off if you do it later, it's alot more work to remove the SC.
Second, if your engine has never been apart, it doesn't take long for boost to expose all the weak points, like gaskets and seals.
Get some TW's or 165's, with a custom cam and good intake, you will make more power and the car will be more reliable. You won't be driving around worrying about your oil and water mixing because of a bad head gasket either.
Stuffing boost into stock heads is never a good idea IMO.
Please don't say you plan to run 5-6 pounds, because everyone says that, then a month later it's pullied for 12lbs.