Definitely include Black Sabbath, and for a Cathedral track I think Ebony Tears is a much better choice than Soul Sacrifice. Also for St Vitus I'd pick either Born Too Late or Burial At Sea.
Black Sabbath - Electric Funeral (Paranoid 1970)
Angel Witch - Baphomet
Pagan Altar - Black Mass (1982)
Witchfinder General - Burning a Sinner (Death Penalty - 1982)
Death SS - Profanation (7 inch A side - 1983)
Manilla Road - The Veils of Negative Existence (Crystal Logic - 1983)
Cirith Ungol - Black Machine (King of the Dead - 1984)
Mercyful Fate - Come to the Sabbath (Don't Break the Oath - 1984)
Trouble - Psalm 9 (Psalm 9 aka Trouble - 1984)
Pentagram - Sign of the Wolf (Relentless aka Pentagram - 1985)
Candlemass - Solitude (Epicus Doomicus Metallicus - 1986)
Saint Vitus - I Bleed Black (V - 1989)
Winter - Eternal Frost (Into Darkness - 1990)
The Obsessed - Brother Blue Steel (Lunar Womb - 1991)
Cathedral - Soul Sacrifice (Forest of Equilibrium - 1991) Earache
Count Raven - Hippies Triumph (Destruction of the Void - 1992)
Sleep - The Druid (Volume 2 - 1992 or Sleeps Holy Mountain 1993)
Come to the Sabbat is awesome...and just about the only decent thing Black Widow did I think...it would certainly show the doom heritage of bands like Blood ceremony and Jex Thoth.
As for St Vitus, I Bleed Black is one of their best tunes though I would possibly go with St Vitus.