I have heard that the 427's were real runners, as for bad , the only poblem with them was the head gasket that was a noticable thing that alot of the engines had trouble with, BUT not all, there are quite a few running strong, i do not think U will find a big difference at all in any..., they are also a superturbo I have heard it called from thenewMv guy, Scot, He was eying the one in the crate at my shop, there is a way bigger ram air type thingy that shure must push an aweful lot of air, its bigger than any on a 465, In my opinion it is also very much a cool factor to have something different than the deuce next to U at a show or event, As for the smoke, the turbo on those and the 465's are there to sqwash the smoke, and they work, I would not worry about that either. so the head gasket is the only thing that these motors were known to have trouble with, and to be honest, Just about none of us are ever going to push these trucks that hard that long, go for it, an Airforce truck is always the one to get, Well taken care of and maintained, and just not used......All the best in whatever U do...Randy