Why would upper control arms be at steep angle?

[Jemo]

This is a basic question, I should probably know but want to understand this better. I have a Mustang 2 front end on my '59 and it's a kit made for this truck. The upper control arm is at such a steep angle it tore the boots on both upper ball joints. I have the ride height where I want it. It's not slammed to the ground or anything radical. Is this because the coil springs are not long enough? TCI told me the springs are 375# and have a 14" free length.