In my opinion, when the main theme starts, it should be in the trumpet. That spiritual style longs for a trumpet lead and if I were to continue the arrangement, I’d start in the trumpet versus woodwinds. Sort of, in a sultry way. With picking a spot to end, why try to tackle the whole piece? You experienced how the first reading session went. It’ll probably be under tempo, so pick a spot where the phrase feels conclusive. In my opinion, about one-minute, thirty seven seconds in (1:37 from the beginning) of the video, Price does a deceptive cadence in the third measure of the system. Instead, make it a PAC and resolve the piece before it goes into the developmental section. This is one suggestion and you can find more spots like this later in the work as more alternatives. So, you have options to pick from.