Rear controlarms on 79 olds

[Pro-Touring79Cutlass]

I have a 79 olds too door ,im in the process of doing a lot of work on i have a 7.5 rearend in it and im going to lower it 2-3 inches in the front and 1 in the rear.im looking at aftermarket control arms for the rear and i have seen a post on a g- body site that if you lower the car you need to use adjustable arms on the rear end becase the pinion agle will be off if you use non-adjustable arms .