It is 'almost' a kit. Another guy did basically the same set up in his P38 Rangie !
I must admit, this engine is really growing on me. I think there was one with a supercharger put into an Ibex competition vehicle with Dynatrac axles and it did well.
That being said, there seems to be some differences between the 6.2 and 6.5 and between civilian and military specs that one needs to sort out.
I tried a very early one in a Seville back in 1978 or 1979 or so, when we had a MB 300D, and that thing left a really bad taste. When the dealer thought we were going to take it (Cadillac invited us to come out and try it) and wanted to let us know how much (little) our Benz trade-in would be, we laughed and said that they would have to pay us to take it.
Apparently, the later ones are much better