Build your own Pedal Assembly
This hydraulic pedal assembly guide can help you select the right parts for your application.
You might prefer the feel of a full sized pedal so this is a good way to go. The only drawback is the gas pedal does not slide on the "super pedal slider".
The single pedal assembly is perfect for your buggy if you have an automatic transmission that does not require manual disengagement of the clutch. Like a CVT on a snowmobile engine. You can also use this as a clutch pedal if you decide to use the new tandem brake pedal.
In some off-road cars a tandem brake pedal assembly is the best way to go. Separating the brake bias between front and rear will maximize the braking efficiency.
First you need to decide if you just need gas and brake, or if you need a clutch system too.
Gas and brake.
Gas, brake, and clutch.