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

This is after cutting out the entire wheelwell, with a borrowed 275/45/20 sitting as low as the inner structure where the well seam was cut away will allow. Sorry about giving everyone the finger :)

More details are in my thread for the build.

http://www.forabodiesonly.com/mopar/showthread.php?t=161976&page=3

I'm posting here with questions. In that position I have about 7 1/2" ground clearance to the frame in front of the wheelwells. I'm not sure what's too low in terms of ground clearance. Up front I know headers don't survive if its too low. I don't want the back much lower than the front. I want to lower the front just to what the torsion bars and headers allow.

I also need to know how much room I need to allow in the tubs for rear suspension travel.

Hoping some who've tubbed and lowered will chime in since its all new to me.