Fireball2,
Here is what you need to read on the subject of making a DR on a shotgun frame. It is known as "the book" on the subject and was written by a gunsmith/gunmaker in Colorado. It is also an interesting and informative read.
Building Double Rifles on Shotgun Actions
by W. Ellis Brown
Buy it from Bunduki Publishing ---
www.BundukiPublishing.com Enjoy
Well, that's the book I'd need to read I guess. Not sure how much closer I'd personally be to my goal after spending the $200 they want for the book, since I probably couldn't do the work anyway, but the knowledge is right there for sure. I'll have to mull that one over. Thanks for the link.