How to put new engine on mini bike with a torque converter?

old engine is a tecumseh 3.5 with a torque converter on it already, new engine i have is a tecumseh powersport 5hp ohv how can i easily change the engine so i can put the torque converter on it without disassembling it too much?How to put new engine on mini bike with a torque converter?you have to have the same size shaft to interchange the torque converter . if the shafts are the same then you'll need a puller to remove it from the 3.5 , to use on the new one.