
^^^
Even If you chose to use a centrifugal clutch, you will most likely still need a larger motor mounting plate anyway, because your old one is probably sized for a smaller 5hp briggs engine.
The motor mounting bolt-pattern on your 13hp is much larger, and the 13hp engine is a lot wider than a 5 or 6.5hp. So the 13hp would also need to be located more towards the center of the kart.
So... you could install a larger motor mounting plate far enough over (towards the center of the kart) so there would be room for the torque converter and jackshaft to fit, and line up with your sprocket.
Or, if you chose to use a centrifugal clutch, just locate the new motor mount so the clutches drive gear perfectly lined up with your wheel sprocket)
You'd need to buy your torque converter, jackshaft and gears (or centrifugal clutch) first, so you could mock everything up to determine all the mounting locations. But your kart
does have enough room to do what ever you want if you do some mods.
From your pic, your kart appears to be an open-axle/1-wheel drive setup.
I prefer karts with a live axle so both rear tires drive the kart. If your going to all the trouble of mounting that more powerful 13hp engine anyway, this would be a really good time to also upgrade your kart to a live axle. Then you could easily use that torque converter that you posted a link to above.