A 216 with a bad engine should be down around $200.
Those tractors are more durable and reliable than the 318, but not nearly as easy on the driver.
A good 16 hp replacement engine is the hard to find unless you want to spend big money. You can replace that bad engine with a K241 at 10 hp, a K301 at 12 hp, a K 321 at 14 hp.
Any of those engines will pull the tractor and run the deck.
Weak points on that line of tractor are the rear hubs (check for wobble by jacking the back end up) and the variator ( it needs to be running to do that.