Manuals are guidelines. Things haven't really changed that much. Older manuals still work. So do the little booklets. Lots of good info on the net too, from various manufacturers. I know you can load up Sierra's whole manual.
A new manual would be nice, but you can definitely get by without one also.
As for the 223, LOTS of powders work well. I like TAC very much lately. Burns very clean.
You can never go wrong with H335.
As far as Varget goes, it is better with the heavier bullets than the lighter ones.
Spin a Hornady 75gr BTHPM fast enough in a 1-9 twist and it will shoot well in some. 25gr Varget gets it done for me. Be careful and work up if you try it.
I'd never be able to limit myself to one powder.......