Droped spindles VS offset bushings
IMO, If you lower the car more that one inch lower that oem spec. the front end geometry goes out the window. Was it all that great to begin with? NO. but with that a fact. you need to be into changing the upper control arms and or pick-up points to achieve more castor, and correct the camber curve. that's where dropped spindles are some benefit. In that you can maintain the imperfect factory geometry rather than make it worse.
If you are only interested in a pleasure driver on the street or straight line stuff it's not too big a deal, but if you want a "canyon carver" then some changes will be in order.
The factory front end geometry NEEDS to go out the window. It was set up for bias ply tires, which have much different characteristics than radials do. Remember, the factory geometry included positive camber and negative caster. #-o
When lowering the car, you don't need to change the stock UCA's. Tubular arms are nice, and I run them on my cars, but they aren't absolutely necessary. Most lowered cars can get enough caster back with the offset UCA bushings to run the alignment specs I posted above, otherwise I wouldn't have posted those specs and suggested that the OP get offset bushings.
Lowering the car does not make the factory geometry worse, either. It actually
IMPROVES the camber curves, lowers the roll center, and slightly reduces bump steer (although this was small to begin with). It does make getting the caster positive a little more difficult, but the offset bushings correct that.
On the flip side, adding drop spindles can make the geometry even worse than factory. How? Because most people don't lower their cars a full 2". If you lower your car 2" from factory with 2" drop spindles, most of your geometry stays the same because the angle of the control arms is unchanged. Camber curves stay the same. The roll center is lowered with respect to the ground, but not with respect to the car. But, if you don't lower the car 2", you actually have raised the suspension. It's confusing, I know. But, if you lower the ride height of your car 1.5" while using 2" drop spindles, you actually had to
raise the control arms. And that makes your camber curves worse. And increases your bump steer. And raises the roll center with respect to the car (even if it's still lower with respect to the ground).
The best suspension geometry for handling characteristics on these cars occurs when the control arms are roughly parallel to the ground. From that point, compression always adds negative camber, which is what you want. The steering arms are almost parallel to the control arms, and they're parallel to the ground, so bump steer is minimal. The static camber is usually negative, and you just have to get the correct amount of positive caster, either with offset bushings or tubular arms.
You don't even have to believe me. The article that covers the geometry changes between the standard 73+ A-body and FMJ spindles plotted out all of the suspension geometry for a lowered car, because the car used in the article was lowered 1" from stock and used 26" tall tires. You can see the roll center, camber curves, bump steer, all of it. The bit about it being lowered is in the caption attached to picture #9 in their slideshow, it's not in the main text. And 1" lowered from stock isn't even where the best geometry is at. :D
http://www.hotrod.com/how-to/chassis-suspension/mopp-0503-swapping-a-and-b-disc-brake-spindles/