Is the engine in a vehicle, or out? How was it prepared for storage, or was it just set aside with no preparation? Assuming it was oil stalled, or fogged before storage, and in a dry location, may not require much, but at a minimum, I would remove all the spark plugs, and take a close look at the pistons and cylinder walls, preferably with a borescope. If it looks OK, squirt a bit of either Marvel Mystery oil, or a light engine oil in each cylinder, change the oil and filter, and remove the distributor and valve covers, and prime the oil pump until a steady stream of fresh oil is dripping past all the rocker arms, and only then, rotate the crankshaft a couple of revolutions, while still priming the oil pump. Check to make sure that all the valves are opening and closing properly (not stuck or sticking). If the engine is in a vehicle, I would swap on a known good carb, and run a hose from the fuel pump into a fresh jug of gas, install the distributor, and fire it up. Obviously make sure the cooling system is full and bled, everything is attached and snug, and an air cleaner is on. A back fire from the carb, or sucking in a bunch of dust, rust, or other crap from the fan blowing stuff around, and into the carb is not a good thing.