After that much time, I would expect most kinds of germs and parasites to be dead, unless they are ones that can live even without a live chicken. And any that are still alive are probably not going to be killed by any kind of cleaning you are able to do.
Also, if you will be letting your chickens outdoors, they will still get exposed to anything that may be lingering from the former flock. So doing an extra-good job on the coop may be a waste of effort.
You could consider leaving the old bedding in, since it's probably nicely composted and the chickens would have a great time scratching through it looking for worms and bugs.
You could clean the coop until it looks clean-- shovel and sweep, then consider whether it's better to leave it that way (dry) or spray down with a hose and then wait for it to dry again. If there is dried manure caked on, spray it with water and let it soak to soften up, then spray again, and consider whether to keep spraying or to use a scrub brush next.
If washing it down with something like bleach would make you feel better, you could certainly do so. I've cleaned things using bleach or Lysol, depending on which I had handy at the time. Either one requires thorough rinsing and tends to leave a smell when you're done, and I think either one kills germs fairly well. I don't think it will make much difference in how safe the coop is for you and your chickens, but I don't think it will do any harm either.