Engine Change?

[Irish]

I'm not sure if this is the correct place but here goes. I just relocated & bought a 250cc Road Warrior Trike. I am fond of the bike itself but am very dissatisfied with the power. In NH , I used to drag race & build custom "Choppers". Everything that I built or rode had much bigger engines. Does anyone know of a bigger engine that would be interchangeable without to much adapting? In NH , I had a lot of connections with welding , parts , etc but I now live in W.Melbourne Fla & know no-one. Thanks,Irish