Cho'gath is a great top if you can handle playing very passive and just focus on out sustaining them from his passive. If you're careful enough until full stacks of his Ult then you become nearly unkillable.
As for Talon though, he is my favorite champ and I would never take him to top. I've played him as adc and it works better then going against those bruisers on top right now. But he's really best in mid, he destroys most AP casters and can roam very well.
For support I'd suggest kayle because of the new support items she can be very powerful, has decent sustain and pokes really well. She can add a tank to your team comp or massive extra damage while keeping vital members alive in team fights at the same time.
But it all comes down to finding who has the best synergy with your play style and is fun, Good luck!