From my research here and other sites.
Some of these kits are absoulute garbage! Bad welds, poor geometry , ill fitting very poor after purchace support and generally unsafe. There's even pics online of some of the component failures and the're not pretty.
I personally used RMS Suspensions and bought the Alter-K- ation front suspension and The Street-Lynx 4-bar triangulated rear suspension for my 68 Barracuda. Works fantastic and no problems after 5000 miles. The owner, Bill Reilly is great to deal with and after sales service is fantastic!
I didn't know about HDK Suspensions when I bought my setup but I definitley would have considered it as it extremely well built and the company receives great reviews for its service. The owner is well known on this site and has been modifying/restoring A-Bodies for years.
Late Mopar A Body Front Suspension Parts 67-76
Whatever setup you use, check it out thoroughly. Your life will be at risk if you buy junk replacing suspension components.