The Leopard is one of the most popular engines in karting so it shouldn’t be too hard to get it sold quick so you can buy a KPV. Someone might be interested in trading, you never know.
I don’t know where you’re located, but the demand for KPVs is very low in the east these days, with the class sizes dwindling many places. You should be able to pick one up relatively easily. The Leopard would definitely be worth more, assuming its in decent condition.