Agree, I think the Cougar looks better with a spoiler but that's my personal opinion. I had the old 'small' spoiler on mine from purchase but replaced it with the Eibach/Visteon wing (which was just over $600AUD a few years back from Ford) very hard to source one in Oz now, except from a wrecker or someone giving theirs up.
Failing sourcing a good wing, definitely look at suspension and cosmetic changes as well as the exhaust etc to improve an already good looking car
Dan