I would have a look at faster radios.

For a lower budget:
http://ubnt.com/nanobridge

for a higher budget:
http://ubnt.com/powerbridgem

5ghz is better then 2.4ghz. 900 is great if you wanted to license it. Both will get you about 100mbps.

I am not entirely sure what the framesync consumes. Of course remember that packets will be slightly delayed going over wireless. Fiber would be the best way to ensure near zero latency between the two locations.

Ryan