$2200 seems fair with a turn key deal if done right. I swapped a 700r4 into my latest 72 swb step and it didnt cost me but about $50. I had the recently rebuilt trans out of a suburban i parted and i only needed a new tv cable and bracket. I parted the truck and made money AND got the trans. Thats how i roll!
Another thing to take into consideration when contemplating an overdrive swap is the extended life you will get from the engine due to the lower operating speeds brought by the higher final gear. You will also experience less noise at highway speeds.