The only thing pinion angle does is control bind or "roping" of the drive shaft. Pinion angle is an U joint and shaft alignment issue only.
The holes in the upper box set where the angle where the rear end pulls back on the car, so they have minor effect on front end lift. The upper arms pull back, they do not push. Keep that in mind.
The holes for the lower arms have the major effect on hit rear wheel separation and wheelie. These are the arms that have all the forward push. If you have the front of the arms mounting bolt higher than level from the rear bolt holes the rear end will start to separate and drive the tires in the track on launch. If you have it around level or lower the rear end will try to drive under the car and roll the front way up. It will also, if the arm is lower enough in the front, make the rear tires pull up off the track at launch and go into the wheel well.
When you get it right, the whole car will lift on launch, slightly at the rear and a controllable amount at the front. The upper arms are really just a fine tune, since they only pull back. The uppers also enter the rear end.
An instant center calculator is quite a bit off with the Mustang suspension because of the geometry of the arms and spacing between upper and lower arms on the chassis. It behaves nothing like my real 4 link car did, where upper and lower arms were both straight forward and each side pair tied into one close point on the chassis.
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89 LX. 363, single turbo, Super Vic EFI, TFS high port heads by TEA, solid roller, glide. Holley HP EFI. (exact combo varies)