I dont think Culpepper is starting for Oakland this week, I'm pretty sure it's McCown. With that said, I still like Porter the most out of the group. Walter & Stokley are both okay receivers yardage wise but do not see the end zone all that much. I think Porter has the best matchup (close with Stokley vs. Det) and should put up some good yards and has the best chance to get a TD. In all honesty, I do not know much about Gonzalez on Indy and I do not think he has done all that much this year. Considering all the passing weapons Indy has I do not think that will change any time in the near future.
I'm not sure I would consider Owens a must start as Philly is going to do everything in their power to shut him down, if I had Crayton & Owens and could only start one I would go with Crayton this week. But, considering your other receivers it looks like you have no choice but to go with Owens. You may want to consider going with Stokley & Porter though, or even Walter & Porter.
Regardless, good luck with whatever you decide to do.