? Front upper control arm bracket? There is the front control arm bracket, the upper rear, and the lower rear - which one are you talking about?
Yep. Won't work that way. You've changed the upper arm pivot point lower, but done nothing with the lower. What shape the arms have really doesn't matter - from a suspension movement point of view. They can be curved, or straight, or go straight down then over, and the suspension movement will be the same. It's a matter of where the two pivot points are. If you leave the stock upper mounting, then put your arc'd lowers on, then it will work properly.
Or you could take the upper, arc it so that it ends up the same distance horizontally from the frame mount, and say 4" lower than stock, and then do the same with lowers. It'll articulate like it has a "standard" 4" lift, but it will have more clearance to the trailing arms. Like this - blue is normal, red is the arched arms. Course, you could also just move all the brackets up on the axle - effectively moving it down. The problem you're seeing is you're talking about running the yellow top and red bottom.