'87 aerostar.... blown head gasket?? PLEASE HELP!!

[nmoran429]

My grandfather has a '87 Ford Aerostar Minivan which he uses as a workvan. Today, the engine and oil lights came on in the cab. Then it started to smoke underneath the hood. I pulled over and noticed that the coolant flushing valve had a hole in it so i went to the local auto part store and replaced it. THen I noticed that I was putting a lot of coolant and water into the radiator. THen as I started it back up again, I noticed water and coolant coming from both the tailpipe and out of one of the seals right before the CAT convertor. I'm not sure if its the gasket, will it cost a lot to repair, or is it even worth it? PLEASE HELP!!