Your common Lancaster style shrinker/stretchers don't have jaws that protrude like that. Only the higher end machines like Eckold or Erco, etc do that, that I am aware of. Check out allmetalshaping.com. There is a whole section on shrinker/stretchers.
Do you have a stretcher/shrinker now? If so, could you just buy replacement jaws and grind them to shape.
I have a Metal Ace setup from them, that I added air cylinders to. https://www.trick-tools.com/MetalAce_Shrinker_Stretcher_Deluxe_Kit_SSF2005_Kit_953 Not the cheapest thing, but I use the hell out of it. Someday I will upgrade to one that has smooth pads, but that is a long way off. My money would be better spent elsewhere.
Check out Karl of Make It Custom on you tube. (tried to attach, couldn't) He built what you are looking for out of scrap metal and an air hammer, made great curved pieces.
^^^ X2. With those Eckold prices you'll need to be going into parts production runs, unless you're charging $200 hr. for custom work or prototype work to get a ROI anytime soon. Those types of tools fall into the specialty, downright exotic metal working tools (Yoder hammer, cast iron english wheels, etc) so you're not likely to find the Eckold stuff used or at auction like the more common (brakes, shears, etc) metal working tools.
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