I have a 91 LS6 in my 79 Z28. I believe it was the last or next to the last year for the crate LS6. Mine is the p/n 366250. List: $4,621.88 Purchase: $2,990.62 1/8/1991. As far as the value today, I'd take a look at what it costs to replace it and go from there. Probably a little more because it's an "LS6." I'm not an authority though...

https://farm5.staticflickr.com/4498/...f86c1823_b.jpgGM Catalog LS6 Specs by Dave H, on Flickr

https://farm5.staticflickr.com/4417/...5e9e1408_k.jpgLS6 PN Description by Dave H



Not exactly right out of the crate...

https://farm5.staticflickr.com/4443/...4f6dd8ef_k.jpg20171017_175306 by Dave H, on Flickr