2wd lift kit questions

[DrFock352]

I posted over in the 2wd forums, but i guess that is the wrong place for lifted trucks. I am planning on buying a CST 7.5" lift for my 2002 Silverado single cab short bed 2wd. This seems the be the biggest kit I can find for my truck at this time. The rep at stillen said i could fit 305/70-17 tires with this lift. I am wondering what tire size that would be if i were to use 18" wheels instead. Also stillen gave me a price of $1540. Does this sound about right or is there any other vendors that anyone knows of that have better deals?