Here are some spring part numbers from the Fat Man Fabrications catalog.
NAPA #277-3039 Mustang II 4 cyl.
NAPA #277-3036 Mustang II 6 cyl.
NAPA #277-3038 Mustang II 8 cyl.
The best price that I've found for the tubular control arms was $400 on E-Bay. The "going Price" is closer to $500. The best price that I have seen for the Carrera coilovers is $370 from Fat Man. Aldan also makes a set for the Mustang II, but I have heard that they are prone to bend at the upper mounting point.
After I did my conversion I sold all of the old parts on Ebay and got a total of about $200, you can figure that in to the overall cost to help convince the wife
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-Jon