High noise environment optimal settings?

We have several towers with very high noise due to several operators on them.

noise floor is in the -70 range, rssi of the customers is in the -50 to -60 range.

The long term solution would be to move to another tower but we need a short term solution to mitigate RF interference issues.

We have changed to 10 mhz channels, are there any other parameters  on the radio that would help with high retransmitions and low modulation customers due to poor RF? 

We are running 2.5 ms, 67/33 split , 5 CS, 2 Broadcast repeat.

Higher contention slots?  2.5 or 5 ms period? Broadcast Repeat Count?

Aside from moving to a smaller channel width (which it sounds like you've already done), and increasing AP and SM TX power to as high as allowable in you region... there aren't any other settings that you could use to mitigate interference. The only other things left to do would be physical... like changing to a 450i AP, or using a tighter/higher gain sector antenna, or using SM's with a high gain directional antenna, like the 450b high-gain SM.

You could check to see what you peak time frame utilization is and adjust it to give relief in whatever direction is maxed out... e.g. if you're downlink frame utilization is regularly hitting 100% during high usage periods, but your uplink utilization is lower then 100%, you could give a higher downlink ratio percentage. Basically steal from the uplink to give to the downlink... or vise versa.

Also unless you're doing any multicast/broadcast stuff... you can just set the broadcast repeat to zero, which will give you a bit better performance.