Well HP=Torque*rpm/5252 and you know the HP and torque you want so really all you need to know is what revs an engine would be turning to get those figures. So you have RPM=HP*5252/Torque which gives RPM=1*5252/2.6 or 2020RPM.

No engine (other than a very large one idling) can produce those kind of figures but all that's needed for a model engine is some suitable gearing. Take for instance an engine that makes 1HP @ 12k revs. To get that HP at those revs it needs about 84 oz-in of torque. With a 6:1 gearing the output shaft torque would be 504 oz-in.