If you have natural wider hips and waist, than you will probably have a blocker look. If you have a natural average, or better still for BBíng, narrower hip/waist structure than a larger rib box will be that more impressive. Giving more support to getting that "V" shape to the upper body. Actually the "X"shape, including the legs/lower body, still tends to be what most BBérs are after. A fuller rib box will not always suggest a blocky look. The chest/pec's & even lats will even look more impressive when build on the foundation of a full and deep rib box.
If doing pullovers (straight or bent armed) the full stretch is the more important part of the exercise. If stopping at near or above the point of being only lever with the head, than you are not reaping the full benefit if this exercise. A pullover is not the best pec movement, as the path of the weight would suggest.
As mentioned before, my favorite exercise is the bent arm pullover and press. With pressing off the chest at the end of each pullover, the triceps, delts and pec's are recruited that much more. Consider the pullover & press as a superior compound movements......a upperbody mass builder.
If you were born with the structure of a flatter bicep, than no amount of concentration curls will give you a peak like Arnolds. Or the impressive double display of a Boyer Coe. If born with a natural peak, than simple BB curls (for example) will bring this out quite well. Muscle inserts will dominate your muscle structure.
If you have to do 20 rep training for cuts. may want to recheck your diet and workouts. 4 to 6 reps seems to influence strength and muscle size, for most people. Good Luck.