High speed stability issues

Five extra degrees of caster will help.
How big a rear tire? And how much tire pressure? Bias or radial? A soft bias slick can become plenty unstable on the big end.
Edit: our local carb guru/mopar lover has experimented with air stack-up relief holes. His nine second 470 street driven dart has a sixpack scoop, sealed to the carb. He says three 1" holes hole-sawed into the rear wall of the scoop made a substantial (?!?) difference in the metering requirements on his dominator.
(I think i might have just removed the carb pan and see what happened).