Welcome to the forum Dawn :)
WOW! That's not something you see every day!!
In unrestored condition I believe it would be worth 2-5k but restored it could be worth up to 25k!
If it were me I'd keep it, but im sentimental like that!
My grandad had an Audi 100 too back in the 70s.
In terms of work required I would thats a small amount for a car of that age! Clearly your father looked after it :)
would love to see it at some shows :)
cheers
steve