Charnock would be an interesting call, he's played a fair bit of rugby at #1 (I believe).
As Carlos states, though, given how he's managed to avoid being involved given our deficiancies at#6, he's unlikely to get a start now.
I would not play Wellens at #1. it may be the best short term fix, but we're already looking up against it to seriously contend bringing home the SL trophy. Better to give a young lad a chance and try and play some expansive rugby, which Wellens stunts.
Charnock and Wheeler could both player either 1 or 6, with Lance filling the other position.
I think swift could be a very interesting fullback, but Makinson isn't a bad option obviously Dawson can also play wing, but we also have a promising youngster in Galbraith (isn't it?) who has a very good try scoring record for the under-whatevers.