I think you should change your line-up a little, but this is just what I would do. My starting 5 in your situation would be, harrison and Walker at guard, Messina SF and Winter and Hundley in the frontcourt. I would drop Poythress to the bench and have him get minutes as the back-up Big. Messina could be the back-up guard then when Brown would come in at back-up SF, but in the fastbreak offense I would rather have Messina getting minutes as SF. Poythress I feel gives you very little, especially at SF, I would have him back up PF and C. The starters would be set to either tired or very tired, or I might go with target minutes just to get more control of minutes in an ideal game of who you want playing when.