First and foremost you will have to decide which Venue is the proper one. Given the fact that you seemingly have to rely on RoomPack 1 (Vienna Konzerthaus) only, I would suggest to give "Neuer Saal" a try, because I think you're aiming for a quite dry and controlled bigband sound and not the classical orchestral hall. Use Main Microphone Position 1 with a configuration that fits your needs, maybe adding a few dB from a Secondary Microphone Position in the center of the hall and proceed from there.
Make sure that the format of the Main Microphone setup is the one you're actually aiming for (5.1 surround, if I read your question correctly?) - otherwise the result wont be the desired one.
BTW: The perfect choice would be "ORF Funkhaus Studio 3" from MIR RoomPack 2 - Studios & Soundstages: This marvellous hall has been built in the 1950ies especially for the (back then) so popular jazz bigbands. :-)
Kind regards,
/Dietz - Vienna Symphonic Library