New rear leaf springs, Mopar, Espo, Eaton Detriot, or Hotchkis

I'm getting ready to pull the trigger on buying some new rear leaf springs for my 340 swinger. It seams that everyone is using one of these companies on their A Body. Espo seems to be the cheapest. I'm kinda afraid of buying from mopar fiat performance,Hotchkis lowers the car and well Eaton is way more expensive than the rest but they are supposed to build from factory blueprints.
SO 3 questions,
1 Who makes the most accurate reproduction leaf springs for my 69 340 swinger?
2 Are Eaton Detroit springs worth the extra $$ ?
3 Who makes the longest lasting most durable springs?