I think you'll need to cut up that spoiler! I'm not sure on its width, but I'm certain its mounts will suit a bootline that:
A) bows out backwards
B) bows upwards
Whereas the ED bootline is flat & square.
Contact EFFalcon about this. I'm not sure if he still uses these forums, but he can be contacted through www.eseries.com.au. He's got the same problem but the other way around: He purchased an EA SVO lip spoiler, and has cut it up/glassed it back together to suit the contours of his EF bootlid.
'91 EB Fairmont Ghia V8.
Pacemaker PH4000 extractors
Meaty semi-twin system
AUII XR8 t/b & maf, ELGT snorkel
BA semi-manual shifter conversion
Electronic shift kit
4.11 Hydratrak LSD
Explorer intake manifold
Contra 16x9 rims, rubber: 225(f)/245(r)
Chiptorque HP2 chip