That is not a Russian ASO you can tell by the heel it has no taper, the Russian anvils have a taper on the heel. It may be cast, but if it was you may have serious problems once you start forging because I doubt you followed proper procedure for welding cast iron (preheat to 500F and post heat as well as the proper rod selection). Even if you did do everything you welds they might fail because cast iron is brittle. From everything I can see that was a serviceable anvil that probably could have been sold or traded for a big hunk of steel to make a proper anvil block.