For me.... not an unlimited space, but a limited space in the form of a very large studio apt..... a former bank bldg in Italianate/Greek Revival/Beaux-Art (just a vision).
Tonally, the organ would be an Atlantic City Midmer-Losh in miniature (52 ranks). Most ranks are unified, enclosed, spread among 4 swell boxes, which are adjoined to one another (an idea I got from a diagram Senator Richards drew up).
Wind pressures at 10", 15", and 25". Softest (Viola Sorda 8', 4') to the loudest (Ophicleide 32', 16', 8', 4'). Italian Renaissance case and console (4 manuals with stop keys). Placed near the center of the banking floor. The Echo would be in the ceiling. My sleeping quarters would be a partitioned-off corner.
Here's the tonal analysis, since a full stop list would take up too much space:
Unenclosed (*= originates on Pedal)
Contra Bass 32' (16', 10 2/3', 8', 5 1/3', 4'); 15" *
Open Wood 16' (8', 4'); 15" *
Double Diapason 16' (10 2/3', 8', 5 1/3', 4'); 10"
Bourdon 16' (10 2/3', 8', 5 1/3', 4'); 10" *
1st Diapason 8'; 15"
1st Principal 4'; 15"
Twelfth 2 2/3'; 10"
Fifteenth 2'; 10"
Double Ophicleide 32' (16', 8', 4'); 25" *
Enclosed A (*= originates in Pedal)
Contra Spitz Flute 16' (8', 4', 2'); 10"
Contra Viol 16' (10 2/3', 8', 5 1/3', 4', 2 2/3', 2'); 10"
Harmonic Flute 8' (4', 2 2/3', 2', 1 1/3', 1', 2/3', 1/2'); 10"
Flute Celeste 8' (4'); 10"
Vox Celeste 8' (4'); 10"
Tierce 6 2/5' (3 1/5', 1 3/5', 4/5', 2/5'); 10" *
Principal 4'; 10"
Fourniture 15.17.19.22; 10"
Double Trumpet 16' (4'); 15"
Trumpet 8'; 15"
Orchestral Oboe 8' (4'); 10"
Enclosed B
Stentor Diapason 8'; 25"
Bass Tuba 16' (4'); 25"
Tuba Magna 8'; 25"
Corno Francese 8' (4'); 25"
Enclosed C (*= originates in Pedal)
Geigen Diapason 8' (4', 2', 1', 1/2'); 10"
Voce Umana 8' (4'); 10"
Gedeckt 8' (4, 2'); 10"
Septieme 4 4/7' (2 2/7', 1 1/7', 4/7'); 10" *
Nonieme 3 5/9' (1 7/9', 8/9', 4/9'); 10" *
Quint 2 2/3' (1 1/3', 2/3'); 10"
Contra Oboe 16' (8', 4'); 10"
Double Bell Clarinet 16' (8', 4'); 10"
Vox Humana 8' (4'); 10"
Enclosed D
Viola Sorda 8' (4'); 10"
Vox Aetheria 8' (4'); 10"
Corno Inglese 16' (8', 4'); 10"
Sassophone Basso 16' (8', 4'); 10"
Echo Organ
Horn Diapason 8' (4'); 15"
Flauto Mirabilis 8'; 15"
Flute Celeste II 8' (4'); 15"
Orchestral Strings III 8' (4'); 15"
Oboe Gamba 8'; 15"
Tromba d'Amore 8'; 15"
Orchestral Clarinet 8'; 15"
Vox Humana 8' (4'); 15"
Vox Mystica 8' (4'); 15"