I've worked a lot on those engines. While they are pretty durable and get the job done, they are gutless as hell. Figure hp range in the upper 100's at best, and torque in the 300's, although I can't give you exact numbers. Fuel mileage isn't the best either, as most average 4-8 mpg in something like that. They were offered in numerous medium duty vehicles like the toter home as a factory "standard" motor, and the others like the 427 or diesels were options. Personally, I wouldn't buy anything with one of them in it, unless I just wanted something to get from point a to point b, and not in the fastest or most efficient manner. They can be hopped up a bit though, but either way you look at it, it's basically an overweight small block. I'd keep looking if it were me.