Blazing his way through Louisiana in early February, Pat Buchanan reinvented himself yet again. His ambition, he told crowds, was to be, we're not kidding, "a Huey Long for the '90s." (Apparently "Franco for the '90s" didn't click with focus groups.) It's a curious aspiration for a conservative Republican. Which planks of the Kingfish's platform will Pat take for his own? Nationalization of the banks? The 100 percent marginal tax rates? The kickbacks and payoffs? Or just the demagoguery -- the exploitation of frightened and ignorant voters? Probably just the demagoguery.