Oh and real 47RH transmissions aren't cheap from a salvage yard unless you just get lucky and find one in a pick a part yard. When I did my conversion the cheapest one I found was over $1000 and had 250k miles on it. Since they are two year only units they can be fairly scarce.
Grizzly's V10 idea isn't that bad except that comes with it's own set of problems as the V10 is obsolete and some replacement parts such as, rocker arms, cam sprocket, timing cover (oil pump) are no longer available anywhere and magnum and Viper V10 components don't interchange. So you would be stuck sourcing used parts should the need arise.