3.79" can make as much or more power by trading RPM for torque, great for lighter combos and/or tigher gears. The problem with the 4" is only on the top because it's tough/expensive to get enough Head flow. A 4" (generally) will ET an automatic car quicker all else being equal though, plus it's so well proven and sorted out, it's tough to make a rational argument against just going for cubes. 3.79" even with a longer 6.200 or so rod still winds up with a fairly heavy piston due the tall 9.58-ish deck height. 9.200 deck blocks are a natural for the 3.79 though