The Version 7 Unix sources compiled on contemporary systems using contemporary C compilers and system headers.

ed and sed should work.

Unix Version 7 tarbomb from https://minnie.tuhs.org/Archive/Distributions/Research/Henry_Spencer_v7/v7.tar.gz

sed has been packaged for Ubuntu. The package is called v7sed. There is a debian/rules file suitable for making a source- and binary-packages.

To install this on Ubuntu:

echo deb http://ppa.launchpad.net/drj/v7/ubuntu precise main |
  sudo tee -a /etc/apt/sources.list.d/v7.list
sudo apt-get update
sudo apt-get install v7sed

(the last step seems to require you to "Install these packages without verification", I've no idea how I go about removing that)

To make the source and binary packages:

cd v7
# make source
dpkg-buildpackage -S
# make binary
dpkg-buildpackage