70 Duster front drum to disc conv.

You're right 70DartMike. DSTR 340's car in all liklihood came with the drum brakes. The common swap from later disc brake setups are 5 on 4.5" bolt pattern. Junkyards and the aftermarket are both sources for swap. If you don't make any changes to the rear then you end up with wheels with two different bolt patterns. You have a much smaller selection of wheels with the 4" bolt pattern. The switch to the larger bolt pattern is worthwhile, IMO.

This page over at BBDart is a good primer for the swap: http://www.bigblockdart.com/techpages/dbconversion.shtml

Moparts has one too but some of the "requirements" are debatable:
http://www.moparts.org/Tech/tech/pages/abody.html