To me the real issue is the king springs are not that great for handling improvements I've found. I've ended up with coil overs and Gaz shocks as have a few friends but also the Whiteline bars are good. Classic swede do upgraded adjustable gaz shocks and they are well suited. They do springs too.
Going so stiff in the rear on the sway bar isn't going to be that great unless you have stiffened the rest of the bushes. Also adding caster to the front made my 740 feel a lot better and that's also pretty simple to do!