Marrakai,
Yes, I have no doubt at all that the cartridge in question loaded with those Woodleighs will make a very impressive buff killer.
The point I was trying to make is that some shotgun to double conversions handle very well while others don't.
That old 444 would be a classic example on how something can resemble a double rifle but handle like a double decker bus!
I'm just a bit wary on building guns from scratch as you often never know what they will handle like untill the job is completed.