The vibration is probably just tire balance, the alignment shouldn't cause a vibration at all. The other possibility is that something in the suspension is loose or broken, like the lower control arm pivot tubes coming loose from the K frame. Or worn out tie rod ends, ball joints etc but it sounds like you took care of most of those.
As far as the alignment goes, the big block shouldn't have anything at all to do with that. Won't make a difference. The ride height does, but that's adjustable with the torsion bar adjusters. The ride height can make a big difference, the suspension geometry changes as the car is raised or lowered with the torsion bar adjusters. At most typical ride heights the offset UCA bushings can be used to get around +3* of caster. That's not a ton, but it's more than enough for a smooth, relatively stable ride. Tubular UCA's are nice as they have more caster built in, usually +5* of caster can be achieved with most of the tubular UCA's out there. You can get a lot more than that with the SPC's, but unless you have power steering you probably don't want a lot more than that anyway.
Really though, it sounds to me like your alignment guy doesn't know what he's talking about. The big block swap has nothing to do with the alignment other than possibly needing to adjust the ride height. But like I said, that's adjustable so he should be able to fix that if it's a problem, and if he knows anything about Mopars. Did he tell you what the actual alignment numbers were? Or what he was trying to adjust them to? The factory specs are for bias ply's, and shouldn't be used for radial tires at all. These are all reasons I bought my own alignment equipment and set my alignments myself now.
