Setting the bias correctly is something of a 'Dark Art', in that the numbers in the tube data sheets don't necessarily give the best results. I take my amps to the local amp guru, and I recommend you find a good tech in your area.

One of my favourite amp info resources is Amptone.com. Some of the discussions on there are pretty old, but hey, we're dealing with a technology that goes back about 100 years! :)