Effects of a shorter spindle.

I play mostly in late 50's mopars and a popular conversion around the scene is to run the Volarie spindle to get disc brakes, because "its all mopar!" This has always struck me as a less than ideal setup as the Spindle is a little over 1" shorter than the stock spindle between the balljoints. Disc Brake conversions are readily available for the cars... so i'm stuck trying to argue that its a bad idea vs retaining the stock spindle, but without much to back it up.

What kind of effect would this have on the camber curve of the suspension? I feel like since it pulls the upper a-arm down and in, that once aligned at rest, the shorter spindle would cause camber to push out into positive camber pretty much immediately since the ball joint is moving out to get back to its old at rest position. Am I thinking correctly about this? What other ill effects would this have on the suspension from a handling perspective?

I'm unfamiliar with the late 50s parts and dimensions, so I can't swag a guess if it would be better, worse, or no different.

It obviously does change its location, but since the upper control arm is still the same length, it has not changed the arc it travels in. The camber curve may be impacted as it moves in this arc. I can see your logic with it moving on this arc as possibly going positive as it transitions through back through its previous neutral point. The length and pivot point of the lower arm can also be a factor in this. It is less than ideal to do this, but how bad is it, I don't have a clue.

The most obvious impact to me is that it will change the instant center locations. These changes will then impact the roll center locations. Is it a radical difference, I don't know. The change from shorter '68-74 pieces to the taller '76-80 pieces does provide some minor improvements on the traditional muscle era cars. Would the change from even taller late '50s parts to shorter late '70s parts make things worse, I really don't know without mapping it out. All the locations of all the pieces impact this so there is not a linear rule that X change produces Y impact as all the inner mounting points and arm lengths on the late '50s cars are a bit different from the late '60s cars.

if going to the taller spindles still makes it short, could a longer upper ball [dirt track part] joint help ? provided one is made that fits your upper arm.

Interesting.... I appreciate the insight on that. I'll measure out a few things as i have easy access to the car and take a few pictures. I'm curious as to what i can do for the car.

In addition to what TC mentioned.

With shorter spindles, the camber will change quicker during suspension movements.

In an extended suspension situation (like on the inner front wheel during sharp cornering fi), the upper ball joint angle could exceed its designed angle of operation and perhaps fail sooner (in time).

If you don't mind going to 15" wheels, you can fab your own discbrake conversion, keep the stock spindles and keep it all Mopar in the process too.
I put '73 Chrysler discs on my '60 and '62 Chrysler NYers while maintaining their stock spindles.