my go to starting point is the SVT 2 pro head, second setting (stock setting), and I increase the comp to just over 12 0 clock, same with the mids, engage the ultra hi button and the ultra low button, use the 8x10 cab with the 421 pulled back and off center.
I eq and add distortion outside of the plugin, but that is usually what I use for demoing bass tracks... still prefer a mic'd cab, personally.