Revision of an English text, I'll correct Spanish texts

I need a native English speaker to revise a document of mine, it is a translation of a book, already translated, with very good English. (29 pages long, comic style, not very long).

I just need to make sure that the English used there sounds natural since there's slang and I don't usually use it.

In exchange, I offer myself to correct essays/activities online, the quantity and time we both agree.

I am a Spanish writer and publisher, so my knowledge of Spanish is very deep and accurate. 

Thank you! :)