I suggest the dart sportsman over the ford R block. The R block cost a little less than the dart sportsman but its requires more machine work from what i have read. Figure an R block will cost you around $1600, and a dart sportsman will be in the $1900 range. The nice thing about the sportsman is that it is machined to accept the stock lifter hold down, so you won't have to machine it like the R302 or run retrofit lifters.