Celestion G12T-75 Guitar Amp speakers

[Yellow]

Hi

I have a friend at work who has asked me about implementing 4 x 12" Celestion G12T-75 drivers, into a DIY cabinet. He has a guitar amplifier, so the system will be a passive one.
I have had a look at some Marshall Amps on the net that use the G12T-75, and the cabinet seems to be about 175 litres in volume.

However, I have seen guitar amps that have "open-backs" like some head-phones.
I honestly know very little about implementing such drivers into a cabinet, and was hoping that there may be some fellow World Audio/World Design people who can give me a few tips - better still, a cabinet design spec.

Some questions I have:

1. Should these drivers be used in a closed-baffle or open-backed cabinet.
2. Should the drivers be wired up as two parallel pairs (what impedance does a guitar amp like? 8ohms, 16ohms or more?)
3. What sort of cabinet materials are best
4. Is bracing and BAF wadding used in guitar amps, or are they just basic open boxes
5. Should angles/deflectors be considered to break up standing-waves as in hi-fi speakers
6. Is any kind of "inductor" used before the drivers to roll-off the top end, or is the natural response of the driver used in a cabinet by itself (these drivers work up to about 5kHz)

If anyone can guide and advise, I would be very grateful.

Regards,

Neil.