Looks clean - has some weird mods I would want to undo over the course of a winter, but mostly bolt-on stuff. The wheels themselves are probably $2000 on the open market - Fikse is a great brand.
Looks like a Dana rear - first time I've ever seen one in a Skylark.
Fairly rare car with the 4-speed. Also nice to see a few pictures journaling the restoration.
Link to 1967 GS 400 auction