You're welcome Redfish I think your son and you will enjoy seeing the steam engine. You can get an idea of the stream size of Injun Creek from my pics it is pretty small but I would bet there are some small rainbows down on the low end closer to the ranger station.
Matt you sure have! The grapeyard ridge trail to it has many small stream crossings like 12 or so. The Injun creek trail has only one or two wet crossings but they are a bit large to rock hop.