No one actually has a "complete" power steering kit, you have to provide the pump and whatever brackets necessary for the engine being used, plus the hoses from the pump to the steering gear. Most suppliers have the power kits themselves, it just depends on what you want. There's several styles being made, the original ram assist system (very pricey), one that uses a later integrated power steering box (not so pricey, but requires some fabrication and relocation of the LF shock), one that uses a Toota 4x4 box in the stock location (not too famliar with that one). There's also a kit that uses a rack and pinion with the I beam, but I don't trust that style, just looks unsafe to me.
I will give you a word of caution, if you do any of these swaps, keep in mind that the post-'76 GM power steering pumps have metric threads. Hoses will have to be custom made (metric on the pump end, standard on the other) for some of these conversions.