Three years is not a long time for storage, especially if it was under a roof.
I would start with a little oil in each cylinder, leave the plugs out because you'll want to spin the oil out first.
Next, crack each oil drain plug, engine, trans, intermediate housing, and differential housing. Don't take them out, just loose and see if any water comes out. Let the water drip, then tighten the plugs back. Check all fluid levels, the power steering, and antifreeze.
You'll need to drain the gas tank. The safest way will be to remove the sediment bowl, open the valve and drain it with a long funnel. Next remove the drain plug from the carb bowl, let it drain. Try to use a clean bucket so you can see what drains out. If it's clean and clear, not cloudy with water, or excess grit and rust, you might get by without cleaning or replacing the tank.
Clean the sediment bowl and screen, replace the bowl gasket if needed. Put some gas in the tank, open the fuel valve and watch what comes out the carb drain. There should be a steady stream, not a drip or nothing at all. If there is a good flow, replace the plug, watch to see that the carb doesn't overflow. Remove the air cleaner hose to watch for dripping fuel.
If there is no fuel through the carb, or it floods, the carb will need to come off and be cleaned. It is a simple job, sometimes it can be eased apart without tearing the gasket. Just clean it up with spray carb cleaner, check the float to be sure there is no gas inside, put it back together. There is how to info on the net if you need it.
If the battery was stone dead, might as well find a good, fully charged battery, or get a new one. Before connecting the battery, look things over around the electrical harness and components. Look for chewed wiring, mouse and bird nests, anything out of place. I like to leave one battery cable loose enough to quickly remove, just in case...
Spin the oil out of the cylinders. Be careful, it will come out with force and make a mess! Put the plugs back in.
Check for spark at the coil. If no spark, chances are the points are corroded from sitting. You can clean them with a point file and some carb cleaner. Check the gap, check out the distributor for side play on the shaft bushings. Check the centrifugal advance, be sure it isn't rusted in position. (The worn bushings and stuck advance won't stop it from running, just something to be aware of).
It should now be ready to start. Those typically don't need much choke, just a quick pull then back open. It will smoke heavily at first from the oil in the cylinders. Be sure it gets oil pressure. The oil pump is above the oil level. Sometimes they loose prime from sitting. Removing the front wheels and dropping the front to the ground will submerge the pump if it needs priming.
Hope this helps, let us know how it goes...