I'll try the AUMatrixReverb straight away and if I find gold I'll be back to report about it.
Thank's for the tip!
Agree with everyone else, although I think you should be able to experiment with Space Designer and find something satisfactory. Space Designer uses an "impulse response" to define the reverb space.
I have Impulse Responses from the great concert halls around the world... also have an impulse response I sampled of the men's bathroom in the University's Music bldg. Makes a very nice small room verb for electric guitar.
This will give you an idea of what impulse responses are available and the care with which some of them are made.
I used many of these on a PC using the free concolution reverb SIR as well as Space Designer on the Mac.