I found a keg i forgot i have had for about 15 years,It stunk when i opened it up!.Yuck!.Anyway It's a 15.5 gallon keg i want to use as a kettle.Any ideas as to a good lid for it once a hole is cut in the top,and how to cut a nice clean hole in the top?.Also i want to use it for my first brew possibly,but I'm not sure if It's too big.I'm going to be doing an extract brew full boil,do you think It's too big to do a boil of six gallons?