not all 78-79 hp44 have cast on wedges, only the gay ones :roflmao:
tech; f-250s have cast on spring perches and are very easy to build brackets for, also have thicker .5" tubes and bigger hubs that flex less. its 8 lug so youll need an 8 lug rear axle but that only means once you realize you need a d60 in the front youre ready to go.
plenty of people have done both 4 and 3 links, youll be fine with either. my personal opinion for a vehicle that sees street use is to go with a 4 link making one upper removable for wheeling. also all of this information is here and could be found within the search, i see youve started using it which is good but use it again.