Don’t worry too much about the engine
I’d change the fuel and filter as a minimum and I’d seriously think about changing the oil and filter if not before almost immediately after its running.
Before attempting to turn it over on the key I’d turn it over by hand first – big socket on crank bolt.
I’d reckon that you might have rusty valves which in turn might give you leaky valve stem seals but that’s no biggy compared to what could be .
Fwiw I left my land rover for 2 years without turning it over and with a fresh battery and the above it turned right over and started.
My old v8 sat for ,5 years and before it went to the scrappies I cleaned the points and dizzy an it too started. Didn’t sound clever but it started…..