Swapping shaft out of my mi predator 212cc to a Tecumseh 196cc/6.5hp

Hello everybody this is my first post I've ever done on here but but anyways that being said here's my question and I'm sorry if my terminology isn't the correct words that please correct me and if you're able to help me out with what I'm asking I've been doing this for years and I feel like I'm mentally mechanical privy but I teach myself as I go from online and internet and Google and YouTube most definitely but here's my question I have a yerf dog go kart it's almost 3 years old but I have a 212 predator motor and the original motor that was on the yerf dog was a Tecumseh 6.5 horsepower motor or 196cc but my issue I'm having is that because it has a torque converter on there and the shaft length is a lot longer than the 212 predator is am I able to swap out the shafts for one another flat where I can put the 212 on there and still have the same amount of length and use it without any problems or would there have to be some adjustments I would have to make I mean I'm going to be all right doing so as long as I don't like something like major like I would have to be grinding down some of the metal or something like that but because I've put the 212 predator on there before and I had the torque converter like so far out there with like a long screw you know what I mean and a bunch of washers so I can push it out farther and it worked not flawlessly and also like running it for saying 5 minutes or whatever you can definitely tell it's wobbling like it's going to be thrown off there and it's smoking so definitely not a good idea obviously you'll be getting it like that but if you guys can let me know if you guys have any suggestions or if they could possibly work when I'm asking so far what I've seen online is that everybody saying no well the few that I've read says no but maybe if you guys have some other suggestions of something that it could make it work I'm all ears I really much appreciate it thank you