I saw a 73-75 top restored perfectly on Ebay that sold for $800. It sounds bad, but think about it. If LMC charges a few hundred bucks for weather stripping for it, $800 all of a sudden doesn't sound so bad for the entire thing. A 76-91 shouldn't be nearly that expensive. The first generation tops would be comparable to the 73-75 ones.
'73 K5
Chevy good...Ford bad