Assuming all your king pins, rod ends and steering gear are in EXCELLENT shape (0.000 slop anywhere), check your toe-in (measurement between tires in front should be about 1/8" smaller, maybe more). Also, is there enough caster in your axle - the kingpins should tilt noticeably to the rear. I don't know a good number for a T-bucket but look at top fuel dragsters; they are at 14 or 15 degrees, 'cause they can't afford not to go straight at 350mph.
All else fails, go to an alignment shop, preferably one who works on hot rods, and let them figure it out. Smarter people would have lead with this advice but I like doing eveything myself, even though I usuall do it at least twice!