The spring definitely isn't helping you any. Don't really see what the upper control arm would hurt other than one side now has new bushings since you replaced that control arm and the toerh side doesn't. The different springs would definitely mess up the balance of the car as one corner is going to be trying to sit at a different height and has a different spring rate and all. Get that spring swapped before you drive it very much, changing tha spring will effect the alignment on that corner too.
Former owner of 94 Bird with DOHC 4.6L swapped from a mark VIII
2011 CTS-V Wagon
1968 Torino was an original 289, C4, fully documented numbers matching car. Now: DOHC 4.6L/T-56 swapped, Cobra intake, IMRC delete, BBK long tubes and H pipe. Dynotech Aluminum Driveshaft, 9" rear with TrueTrac and 4.11's.