Public Domain Question

[d]

I have Dvorak's Symphonies 6 & 7 printed by Dover Publications, ISBN:
0-486-28026-8 CODE: 28026-8.  The back cover has the following information,
"Unabridged Dover (1994) republication of the edition published by N.
Simrock, Berlin, 1882 and 1885."  I know Dvorak's works went into public
domain in the mid 1970s but I do not know all the laws behind publishers
retaining the rights of a composer's work.

The following information is given at
http://www.mutopiaproject.org/legal.html.
"When an editor (or arranger, or typesetter) makes changes to a composer's
music, the edition he creates is a "derived work". The editor then has the
right to restrict the reproduction of this edition, as well as the composer.
It is not until both the composer and the editor have been dead for 70 years
that the copyright on the edition expires and the restrictions on the
edition are lifted. Works published after 1922 in the USA may be subject to
additional restrictions."

Now my question, since this Dover publication states that it is a
republication of the Simrock edition published in 1882 and 1885, and this is
not an edition that has altered the original publication am I free and clear
to copy this score note for note into Lilypond and distribute it on
http://www.mutopiaproject.org?

Thanks for any assistance,
David Hughes