I looked at going with a dropped front axle (~3") but I ran into several problems there too. My truck is a 150 series..(ie 3/4 ton). I can find the axle easy enough but then finding new 1/2 ton spindles and then custom forging the steering links appeared a little daunting as well.
In any event, if your shocks are getting that hot to burn off paint I would say that you need heavier coil or leaf springs.
Keeping the 270 in and dropping in the IFS is what would set this tuck apart, in my opinion at least. How many shows have you seen this combo: 57' GMC 150 series, original rebuilt 270, and an IFS with all around disc. Odds are you rare you have seen a 55-59 pickup with an IFS and the 270..let alone it being a 57'gmc (arguably one of the rarer tucks to find now from that time period)
I have decent welding skills and can fab some sheet metal, but to do the job right I think I would need a true fabricator to modify the oil pan.
