Ever see the Blue Angels' C130 do it's JATO takeoff at an airshow? It's a real 'OH WOW!' moment.

The 1.2 hp rating of the engine is at 15,000, so the actual power you are producing at say 11-12 K would be much less. Full size aircraft often have constant speed props, allowing the engine to turn up (and make full rated power for the present conditions). Climb rate of any airplane is proportional to hp (truckers climbing mountains roads are also bound by simular equations).

Good luck, let us know how it turns out.