I think he's referring to a more complete kit that requires fewer additional parts and less fabrication, with an exhaust system that connects directly to the existing pipe, linkage compatible with the original, etc.
That would be specific to an individual chassis (truck vs. Nova vs. rod vs. Impala), and more expensive.
An advantage to buying a blow-through car is that it comes pretty well jetted (well, as close as you can give the specs), and they talk you through minor adjustments after it's running.
There is some good info on modding carbs for blow through on many BBS, including:
http://web.archive.org/web/20070810125306/http://www.vs57.com/carb.htmI have some comments on my page here:
http://victorylibrary.com/mopar/blower-carb6.htm
