20s for the Demon - how low can I go? (big wheel haters don't look)

Sorry it took me so long to reply but here goes.
The rear end is an A-Body 8&3/4 with Moser axles and SSBC rear disc brake kit, no wheel tubs, the wheels are American Racing Rev 100s.
The front wheels are 17x7 part # 100s 7706500 w/4" backspace and 215-45x17 tires with no spacers and factory disc brakes in front.
The rear wheels are 17x9 part # 100s 7906500 w/5" backspace and 275-40x17 tires.
I would like to lower the rear a little bit but at the present time I'll drive it as it is.
Hope this is helpful. :toothy8::toothy8::toothy8::toothy8:
holmes