@Dmartind An Edgun Lesley 2 (L2) may fit the bill. Although the 9mm version seems a bit on the weak side in that caliber, calibers can be swapped and you may want to swap between .30 and .357, or .25 and .357. I have never hunted iguanas, but I've seen videos of people hunting them with .25 and .30 calibers. When hog hunting I'd think you'd want to be within 50 or so yards with this setup as well making brain shots. Let me find some links to include here so this isn't just me talking. Aside from this suggestion I don't know what to tell you. I don't own guns that are made to swap calibers. Whatever you decide, just be sure that you are licensed and abide by laws and regulations set by the state and wildlife agency where you intend to hunt.
Iguana hunting with the L2 in .30
Leshiy 2 Hog Hunt. I thought they used a .357 here, but it's a .30 caliber setup as well.