No expert here either....but I would stay between 800-1000 crossover frequency. I've used Altec 421's with this type cab with approximately 54 sq in ports with good results. Diffinitely pad down the 808's with an L-pad and series resistor. And use a bypass cap of 1-2 uf to eq the horns. I would also listen to each of the drivers independently of one another. This may help to reveal any anomalies within the system and the drivers themselves.