If memory serves, Mustang has springs mounted seperately from struts, if so struts can be changed by jacking under lower controll arm and simply unbolting strut on both ends. When lower bolts are removed spindle will go back to place without any worry of realignment. If upper end can be unbolted and mount left attached to tower, no alignment is necessary. If mount must be removed with strut, MUST be re-aligned.
If I am wrong about springs, and they are around strut, all bets are off. Take it to a pro.
Bob