I've never swapped frames but it must be more difficult than just backspacing wheels. You will have cab mount issues. Then you'll have to deal with your front sheetmetal, grill and etc. Your bed won't fit the frame either. A lot of extra work. You will probably save a few bucks but you'll spend that on a divorce.
Everyone sees things differently, but from my frame of reference I would put a 10 or 12 bolt GM rear with open drive and a Mustang II IFS.
Just my 2 cents...
