Welcome to the forum! I look forward to seeing this build
Those tyres look suspiciously like Harbour Freight dolly wheels, which are a enormous No-No because they just fall apart in 5 seconds. Where did you get them from, and are hey gokart tires?
The exhaust on these engines point directly at your head, so unless you can somehow make a new exhaust and reroute it another way, then you are going to have problems. The shaft is also a smaller size, making it hard to find appropriate clutches