wyowilly46,
I don't know a mechanical reason that it wouldn't work provided there is enough steel there to accomodate the retaining boss on the firing pin retainer... BUT definitely get a new vented firing pin before shooting it... Now that I have said that, the recommended way would be a new breechblock...
BUT if you have the time and the tools you could do it... the question: Is there really enough steel on the bottom of the breechblock to do a good job? and will the damage to the upper portion enable a good fit of the retainer when the retaining boss is turned down instead of up.
Since the block is already damaged, you really don't have anything to lose by attempting this modification except maybe your hand! <img border="0" title="" alt="[Eek!]" src="eek.gif" />