I just had to replace the alternators on both my 74 Chrysler New Yorker "Bluesmobile" that I had recently picked up, as well as, my 76 Monaco Blumo. I had two options - a 65 amp or a 114 amp unit. I wanted the 114 amp but it was oversized for the car. The bolt holes would not line up and it would have required a custom mounting bracket.
My recommendation to you is to select a unit of at least 65 amps. I'd say about 99% of all C-body cars from Ma Mopar had a 65 amp unit. If possible, take the old one with you to be certain it is a match. Too low of an amperage will not power the car sufficiently under a load (lights, wipers, defroster, etc... all running at once). Some of the units on the website you linked too do not show an amperage for each alternator. I have provided links below to equivalent alternators from stores in the U.S., and to the site you provided in the U.K. Be absolutely certain to also replace the voltage regulator with ANY new alternator, and check the condition of the ballast resistor and ignition control module. Hope you have a ballast resistor in the glovebox too! It is a Dodge tradition!
Advance Auto Parts -
Alternator by Standard - Part 5030013 - Advance Auto Parts___
AutoZone Auto Parts -
http://www.autozone.com/autozone/catalog/parts/partsShelf.jsp?displayName=Alternator¤tPage=1&categoryDisplayName=Electrical+%26+Lighting&navValue=15700086&itemId=86-0&parentId=57-0
Napa Auto Parts -
NAPAONLINE
Of the alternators listed at FamilyCar, here is my reccomendation to you - select the AutoLine XCL7544 at this link as it most closely matches what you need -
Family Car - Auto Parts and Accessories Catalog -
Hope this helps. By the way, if you only need one groove of a 2-groove alternator pulley, use the groove closest to the alternator.
"This is glue. Strong stuff!"