A poor craftsman blames his tools!
I know that does not help,:tongue: but when I first got my NSX I thought the pedals needed to be different to heel and toe, but I found out the problem was not the pedals, it was me. Bigger pedals can help you learn, but the stock set up is really pretty good, one just needs to get used to the technique. The one thing which is a bigger help than pedals is shoes though, driving shoes are HUGE as far as heel and toe ease.
Try placing your right foot on the brake pedal with the right edge of the pedal aligned with the center of your foot, (the ball of your foot behind the big toe firmly on the pedal). Now roll your foot to the right so you can hit the throttle pedal with the right edge of you shoe. I find an exaggerated movement of my right knee to the right helps get my foot rolled over to the throttle pedal.
One can also adjust the height of the pedals so the 'home' position of the clutch, brake and throttle pedals are all close to the same position above the floor board. Move the seat close to the pedals so your legs are bent, this will help to move your feet where they need to be, plus keeping your heel up off the floor will help to make the foot roll feel more natural. All of these steps will make the next step of left foot braking be an easier step to achieve.
Now practice, I use this technique when I drive my NSX, or my Tacoma PU, always rev match and heel-toe every down shift. Make it so you do this when ever you are behind the wheel, after 4 years straight of doing this when ever I drive it has become pretty natural. And as long as I practice every day I stay pretty good at it...