Video 8/Hi-8/Digital 8 are very sensitive on playback, especially as they age. The sound quality and picture quality can vary dramatically depending on the player used to play them back. The tracking is also very delicate so some tapes don't play well in some (or even most) machines.
To do it right is time consuming and often trial and error even with good machines. The stand alone Sony players are the best but there's a lot of variation among them. The more expensive ones definitely give better results but due to the iterations in development of the original technology not all tapes play best on any one generation of machine IME.
I'm not sure camcorder playback is too good an idea unless its the same one they were recorded on.
Good luck. If they're really of value and worth doing right it's a big project.