Two more thoughts...

1.) Zimmerman EMACS (a.k.a. CCA EMACS) ran on the PDP-11 originally when Steve wrote it at MIT.  It's the closest to the original ITS/PDP-10 emacs of all the originals that I knew.    I'm pretty sure he converted it to Pavel's freely available terminfo implementation at some point (when he was at Masscomp), but I think the original Zimmerman code has screwed down terminal support to a couple of terminals that were used at MIT.   I've lost track of Steve, but I'll see if I can find you an email by reaching out on an Alumni list.

2.) I believe the first (joy created) termcap was in 2BSD but I don't think Arnold and Horton had started to pull the curses library out of vi yet.  I think termcap itself had been but Mary Ann would be more authoritative than I.  Check out the 2BSD, 3BSD, and 4BSD releases and look for the earliest versions.   The C compiler is pretty much the same in all cases (the only issue I can think is that by 3BSD folks at UCB had removed dmr's 7 character variable limit), but I think curses should compile without too much issue on a virgin dmr V7 compiler.