I second Bushy, you really need to just set it up on your desk first with some small antennas and play with the settings. Get it working how you want it to work, THEN go out and hang them on your towers. Otherwise, you'll just be flopping around like a fish on the deck trying to get it to work.
To answer your question, provided you have good radio LOS you should be able to get 20Mbps or so through that link.
If you don't know if you have good radio LOS, you need to google for "radio mobile deluxe", which can tell you everything you need to know about your point to point link.