I'd go with a Kimber K6s 357 magnum over a Ruger SP101 in 327 magnum. The Kimber is a bit smaller and 4 ounces lighter, but still a 6 shot capacity. At 23 ounces, it would be comfortable to shoot with just about any 38 load, and manageable with lower end 357 magnum.If she prefers a revolver this is what I'd look at. With the variety of ammo they shoot you can find loads from powderpuff recoil to very good defensive rounds. I'd do that over any light weight 38/357.
327 magnum is a good round, but unless you've already got a good stock of ammo, you might be out of luck trying to find any significant quantity. Easier to come by 38 and 357, and the powder puff to magnum load availability still applies.