If your EML is not lighting up with a fault then the Lambda sensors are ok. Probably best not to disturb them if all is well to the cat outflow side of the exhaust. Keep the corrosion around the sensor mounting ports down as rust tends to hold water and increases failure and pressure damage to the sensors, especially the down stream one. I just annually use a small wire brush, preferably a brass one as this tends to leave a brass surface residue and seems to help with corrosion prevention. For what its worth, I think you have made the right choice and stainless brackets too are the way to go!
