I highly recommend Mr. Hien.
http://www.tripadvisor.com/Attractio...Minh_City.html
He was born & raised in the Delta. His family still lives there. He knows the area and the people. I have been on 5 private tours with Mr. Hien with 4 trips to the delta.
Also do not rule out the Cu Chi tunnels. There is a lot to see without going into the tunnels.
Any specific questions, feel free to PM me.