Drain the old gas. I would want to have some lubricant in the bores before turning the engine over with just the starter (no spark plugs) to prevent wear. At that time, check the compression in all the cylinders. I would be listening for the fuel pump to energize. New oil and filter Only then consider attaching the plug wires and attempt to start up for a short run at idle. Listen for timing chain slap at startup, which may signal a non functioning chain tensioner.