I think it's best to take a look at a vendor or two out there and see what they have and how much they want for it.
Don at WCCC has
new inserts for the badges (this replaces the faded or grunged 7.0 Litre emblem that yours seems to have. $35.00 for the insert. A set of
two reproduction badges he wants about $305 for the pair.
As yours is original, it might have some value as-is.... But I personally would only want it if it was cleaned up. Still, you probably would want to advertise it as it stands, as someone else might want it the way it is.
I don't know what it's worth. I would guess that you could start it between $125 - $150, but I've not seen one like it for sale in a long time. I hope someone who knows more about these will chime in. Sometimes you get an answer like "it's worth whatever someone will pay for it.
You could always post it out here in the parts forum and see what kind of offers you get. Maybe it's only worth $40 - $50.
I ended up paying way too much money for what was supposed to be a box of Cougar parts. Turns out there is a bunch of 61-63 fairlane stuff in there and some most definitely non ford parts but what really caught my eye immediately and the reason I paid too much money for the parts was an original C7WX-16098 FoMoCo GTE 7.0 litre fender badge
Please someone tell me it's worth a small fortune

My wife is giving me a timeout right now to "Think about what I've done"..