If you're running a high end engine like the 421, you should know that every engine will tune differently, there's no magic setting.
If you're totaly lost go back o the stock settings and work from there.
many people complain about having trouble setting engines like the 421 or Rb these engines do not have very good low end you have to get a late engaging clutch and a low to mid range pipe.
Good luck, i hope this helped a bit.