Mild 340 street use only will use a stock clutch set just fine. Why complicate things???

Rockauto is your friend in this case:
http://www.rockauto.com/en/catalog/plymouth,1970,barracuda,5.6l+340cid+v8,1496494,transmission-manual,clutch+kit,1993

Generally speaking, the diaphragm clutches have lower pedal effort than the Borg & Beck.

Here's why you don't need anything more than a stock type clutch: factory engineers were very good at matching clutches, transmissions, etc., to the engine in front of them. If you have hopped up your 340 mildly or even majorly, without a power adder the engine's torque will not increase over stock or at most, add 10%, which is well within the safety margin designed into your stock clutch. What increases the power is moving the torque peak higher in the rpm range. But it doesn't matter what horsepower your engine makes! What the clutch sees is TORQUE. So unless you use nitrous or supercharger/turbocharger the torque stays close to the same, meaning the stock clutch is adequate. The farther you go from originality, the greater the chance of reducing driveability.

BUT if you really have to spend $500, then either the Centerforce II or Dual Friction is a very nice setup which will last forever in your application.

R.