lowering question

[cstm68]

so i am going to be buying the disk brake upgrade kit from cpp, it is the (grand slam) # 6770gsk6d the kit comes with all the brake parts, 2 1/2 drop spindals and 4 coils and shocks. it gives me the choice of how much i want to lower the truck.

if i order it with the 4/6 drop coils and the 2 1/2 drop spindals will i have problems with rubbing in the front fender well?
my tires are 275/40/20 ?

does anyone have 4/6 coils with 2 1/2 spindals??