Seems like pretty straight forward setup, 8 zone controller should work for you.
You may have trouble connecting all four of your common wires to a single C terminal on 8 port Rachio, I recommend you split them into two pairs and twist the ends of each pair together before inserting them into separate C terminals (you will have 2 of the C terminals on 8 zone version).
Alternately get a cheap wire nut from your local home depot or lowes and twist all of the commons together with a new wire going from newly made bundle to one of the C terminals of your new Rachio. This will allow you to leave a second one available just in case.
