Hi
Unfortunately, there is a limitation in MS Kinect SDK which allows to use only a single Kinect v2 camera per PC. So you'll need 2 computers and do a
distributed recording with 2 Kinects. For recording with Kinect v2, the desktop you mention is more than adequate. You can use an inexpensive laptop (preferably with Intel Core series CPU) as a secondary PC for other Kinect.
Do you plan to use this PC also for processing records in Mocap Studio? Although it is not so critical for depth cameras (depth videos are processed faster than color) I'd still recommend you to look on configurations with more decent GPUs. Event the next in line GTX 1060 is expected to provide about 50% more performance (and tracking speed) than GTX 1050 Ti.