From memory the standard V6 ecotec converter has a stall speed of about 1800rpm.
I'm certainly no expert but there seems to be some mis-conceptions about high stall converters. High stall converters would only flash to their rated stall speed when a lot of torque is applied by the engine i.e. when you mash the loud pedal. The point of this is to allow the converter to slip so that the engine can get further into the torque band allowing for better acceleration. When only a small amount of throttle is used as per normal street duties then the converter will engage a lot sooner. Modern high stall converters are a lot better than the earlier loose converters we all hear horror stories about. A quality modern high stall converter would only slip a couple 100 more rpm than your stock converter and really won't effect the way the car drives until you get stuck into it.
As mentioned above, due to the fact that the converter will slip a little more than the stock item, a large quality external transmission cooler is highly recommended.
For the late model cars which have lock up converters, as long as you don't want a huge high stall (generally the higher the stall converter, the smaller the converter is and there is no room internally to fit the lock up clutch), the lock up function can be retained so your highway cruising mileage will not be effected. Tweak the tune so that 3rd gear lock up is utilised more for even better results
When it comes to sizing the high stall converters, most shops will ask a dyno print out showing the torque/power curves. On a stock V6 I really don't think you need more than 3000rpm. I'm about to fit a 2800rpm converter so we'll see how that goes.