Engine swap Peugeot Kisbee 50 4t

Hi, first post and hoping some with experience can help

Bought a Kisbee 50 4T Xmas time with a seized engine. Was easier to buy a complete replacement on ebay which I've fitted. Then de-restricted it on CDI and now pulls a good 70-80kmh

I use it for a daily commute & would like to stick a bigger engine in there and see this https://www.ebay.co.uk/itm/315070762391

50CC GY6 Single Cylinder 4-Stroke Complete Engine Motor 743MM Short Case

The bit I'm unsure on is this short case. I'm learning the GY6 do a short and long case but have no idea what the Kisbee is

Any help would be appreciated. The ped was cheap (£50) & cost me £125 for a similar year engine & another £50 or so with a fresh battery, starter relay & lever. Its a great cheap commuter