Will,
I'm not sure why Stonewall Creek thinks building a blunderbuss is much different from anything else in the way of a long rifle or pistol or fowler. I want to build another one that is just a plain working gun...no carving or engraving, just good architecture well executed. The barrel, although larger in diameter, is a lot shorter than a fowler, lock inletting is exactly the same as is putting a trigger guard or butt plate in place. In order to do any of these types of guns well the builder needs to have or to develop a proficiency with tools, manual dexterity, and an eye for the design. (I am trying to improve all of those each time I start a new gun). From my point of view, it is just as easy to learn while building a blunderbuss as anything else. I say, don't let the bore size or Stonewall Creek intimidate you and go for it.
Best of luck.
Dave C
