The 27-year-old has been the subject of talks with the Hammers, with an estimated offer so far of £22m.
Porto are hoping to sign West Ham's Cheikhou Kouyate, which they would want to lower the fee for Marega.
West Ham are looking at Marega to provide them with a more consistent attacking alternative to Javier Hernandez, Andy Carroll and Jordan Hugill.
Corinthians' Angel Romero had been discussed, as well as the option of loans or free transfers.
Romero, who as 13 caps for Paraguay has made it onto the radar ahead of the transfer window closure on August 9.
With the Brazilian season having already started, Romero has had a chance to show what he's made of, scoring four goals, and making five assists in 15 games.