Cost to Replace Gas Tank

[Mulv80]

I pulled a tank from the last V20 I had before I took it to the dump. It was not a job I wanted to do again. Anyway I started removing the tank today, I pumped out about 30 galons of gas water mix and removed the foam and 2X4's that hold down the tank. I filled the tank with water to purge any gas vapor which may have been left in the tank. I plan to cut the top of the tank off with my reciprocating saw. Is this safe?