magnum power steering pump with serpentine belt adapted to 73 power steering box?

Re belts, I downloaded a Gates catalog which has both V & multi-V belts w/ all dimensions. As I recall, they come in 2" circumference increments. V-belts are in 3 different widths. Multi-V come in several "number of V's", most common being 6 if the main belt.

Re p.s. pump, I think all Magnums used the Saginaw (GM) pump, which started ~1973+ for all bodies. As best I have found, the fittings on the gearbox varied with the pump (TRW, Federal, then Saginaw) and you can swap just the spool valve body and return to get the correct fittings (if you can find them, but small so cheap to mail).