magnum 360 into a 74 duster that had a slant 6

Additional Stuff for a Magnum: DUI Ignitions has a very small, hi quality distributor. If you order all the pieces from them you will have one source for any possible warranty. (Plug wires, Distributor, Rotary button and Dist cap, 50,000 volt Coil.
As for the water pump assembly: I used the complete serpentine set up; includes the water pump, A/C compressor, alt, and tensioner. (Uses one factory bracket from a Magnum powered Gen 2 Dakota. Pictures of my set up are posted in "photo Garage" under Triumphman.