Looking for male singer for collaboration.

Im looking for a singer for collaboration in two of my tracks. They were basically made as a remix for a contest but the whole track have been writing by me. I just need to change the vocals and come up with something similar but nicer. As a collaboration I just can offer you to have your name in the track and share the royalty if songs get signed. See this as a possibility of promotion and also as a beginning of a collaboration friendship with me. No money to offer unfortunately.