Plans are found in places like the Model Airplane News web site, the AMA web site or RC Modeler web site. Kit plans will do you no good at all because they do not show any of the ribs or former profiles for you to copy, you need builders plans.
The brush cutter engines also need to be modified for RC use, there are web sites for that too where you can buy some of the parts needed. There are places here on RCU also in the gas engine forum.
Are there any modelers or RC clubs in your area where you can get some help getting started?? You are going to run into a lot of problems just getting something off the ground and you may want to think about buying some used gear and equipment, maybe even a used plane that has everything already installed.
Just a thought.
Glow engines are a better place to start and I'm sure in your area or country people are blending there own glow fuel to keep the cost down, FAI fuel has no nitro, just alcohol and castor oil, it may be a better way to go.