ive got a 13" mountey on mine, with no power steering and no self cancel, i think its great! Really do.
Dnt like the self cancel anyway, cos on mine it was too sensitive cos it was knackered.
About your sound system mate, make sure the locks are good!!
Seriously though, in mine (When its all finished) I will have
Pioneer Bluetooth/Ipod Headunit
1xLightning Audio amp driving 2x 6x9's (JBL)
1xFLi (it was REALLY cheap from halfrauds, where i work) amp driving 2x 8" Kenwood subs
The headunit will also drive 4x smaller speakers
All the speakers will be in custom hand made boxes from 12mm ply, lined and covered to match the dash for the front ones, and the red carpet i was given to line the rear in the rear.
Works out at about700watt all in.
Personally though i wouldn't bother with the air con, ive never thought it needed on a LR, jus open the vents in the front!