Putting rifle barrels on double shotgun actions can work well or not at all depending on the action and the rifle caliber. I put a set of 30-40 Krag barrels on a SKB 20 gauge action and it didn't work out. The action would try to spring open when fired. I didn't discover it until I was down to final regulation and putting the ribs on. It was a waste of time and money.
If you're serious about trying to put a set of rifle barrels on a Parker action I would get in touch with Ellis Brown :
www.ellisbrowncustomshop.com or
ellis450@hotmail.com.
He literately wrote the book and taught classes on "Building Double Rifles on Shotgun Actions". He's a super nice very helpful guy. He can tell you how to select an action for such a conversion. And he of course does that type of work.
I love double's whether smooth or rifled and have looked at and considered buying a double in 405. I don't need one but I would sure enjoy one.