Extensive Water Damage

Hello all. I recently bought a 91 Range Rover, brought it to running condition, and proceeded to submerge it in a great deal of water. It appears that I have water in both my oil and fuel, apperantly leaked in from the bottom as opposed to the engine itself. But at this point, muddy water is all mixed up in the engine. Any idea where I should even start repairing this-- short of tearing it down and rebuilding it, anyway?