BioMax
+1y
You are asking a very broad question.
Do you know for sure that the Datsun would beat the Toyota around a track? Or are you assuming that because the Toy leans more into the corners that it doesn't handle as well? Chances are that the Datsun feels better because it is a smaller truck and has less travel then the Toy, but the Toy probably has more potential.
Neither one of these vehicles are very good handling ones to start with. So several changes would need to be made in order to make a G-machine out either one. Simply installing a stiff sway bar is not the easy cure. In fact, an overly stiff bar can hurt handling, a sway bar should be used for tuning not fixing (although they are quite often used for fixing.)
Go buy Tune to Win by Carroll Smith and do some homework. There is no where near enought room on this site for dynamic theories and handling characteristics.
For an easy bolt on improvement call Bilstein and tell them what you are trying to accomplish, some good shocks can do wonders.