Make sure you don't have a ton of carbon build up on the exhaust valves. It's a good time to clean them up. Make sure the head and block are still straight. Make sure the valve guides aren't super worn and leaking. Check the lifters and cams for potential issues. It just depends if you are trying to keep the motor running or if you want to do some modification. I'd just get a topend gasket kit and some new head bolts and slap everything back together if it's just a street car. It's a great time to replace all the heater hoses, thermostat, plastic cooling passage, and water pump too.