Nice suggestions. I've been thinking about doing an early RPG, too. Lots of good games out there. I could do Temple of Apshai--a great early CRPG that doesn't get much attention these days (overshadowed by Ultima and Wizardry). I'm very tempted to go way back to PLATO. Lots of good CRPGs and space games on PLATO that will blow your mind--seems incredible that they were doing that stuff back in the 70s.
I did think about Zork but not sure how it'd work in terms of video. I've been wanting to cover Deja Vu "MacVenture" from ICOM Simulations, but that's a Mac game. I have the Mac emulator setup for it, but I'll be damned if I can find the Deja Vu disk images.
I like the idea of doing SMB so I could bring in another platform (NES).
Wow, you guys have given me a lot to think about!!!
Dune II is definitely in the future. We dedicate a chapter to it in Vintage Games as well.