some people have had problems with the power disc setup from SSBC with the 9" booster. i wont condone anything made by SSBC until they rectify the situation.
the CPP setup you showed does not attract me either. they need to get their ship together. they are talking about 2 different kits in the same paragraph. first it is a drop spindle kit, then it uses the drum spindles. the pic is of one which uses drum spindles. i personally would avoid it, but it should fit. it looks similar to the scarebird kit. if they use the little 2.5" calipers, i would not get it.
if you buy a manual disc kit, you can always add a stock style booster. i would probably just find a mini kit and get the rest at the 'zone... or find a doner vehicle.
IMO rear disc are mostly for looks on street vehicles, but they provide better brake cooling for race applications. you have to pay attention to brake balance when you stray from stock. any variation from stock, front or rear, can drastically affect balance, and must be compensated.
that's my 2 cents, but i can go up to a few bucks.
edit 2 more cents http://www.classicperform.com/product-pages/camaro/6769SWBK-S.htm this one looks better to me.$50more than the one you posted. it looks like Abody calipers and hoses (that's a good thing). all you would need is the master or master/booster combo and booster accessories. looks like a decent price. you could do it a little cheaper with a little more searching and/or work. i can't recommend their booster or master.