my favorite version also, except for a Z/28 RS...
turns out, my Z/10 was the only one left with the original motor too. I could have paid for one of my kid's college had I held onto it and sold it just a few years later.
I'm planning on getting a '10 Summit White, with the black/orange interior. Add orange stripes and, voila!
yes, it's a Z/10... 350/TH3 speed auto, posi, numbers matching, etc. etc.
unfortunately, I no longer own it....! I sold it about 7 years ago after owning it for over 3 years.
I love that version of the 69... RS/SS, with hideaways and Z/28 stripes.
thanks for asking....