Thanks for this nice show of information digging. One up.
Had done it a long time ago.
Posted it in another thread a couple of months ago. It was just a matter of finding the thread.
From this list,
Filip Dewulf(RG 97), Bob Giltinan (AO 77 Dec), Vladimir Voltchkov(W 00)
John McEnroe is the only other male player to have achieved this(W 77)
In case you are interested, Christine Dorey(AO 78) and Alexandra Stevenson(W 99) are the only WTA players to do the same.
No qualifier(ATP or WTA) in the open era has ever reached a GS Final.