what's this car worth
 

my brother is talking about selling his car but we are not sure what it's worth
it's a 98 z28 with the rs ground kit, a flat black ss hood, has 71000 miles on it, rebuilt 6spd with a spec 3 clutch, comp cam 28-230 @ .5 571-573 112 lobe center, granatelli mass air, 160 t-stat, ngk tr-6 plugs, 4.11 gears, hooker long tubes with dual 3" with x-pipes, nx 150 shot car is non t-top has tan leather interior driver seat torn also has a tune from hpe, car ran 11.40 before tune and spinning, haven't run car since tune how much do you think we should ask for it?