T56 in '63 Impala, looking for master cylinder firewall mount adapter source

I know I saw one a few years ago and they still seem to be somewhat common for other applications but I can't find one on Google now to save my life. Does anyone know where I should look? ...I rarely get this frustrated with Google.

It doesn't seem like the most difficult piece to fab but it might also be a case of speeding the money and putting the time elsewhere.

Thanks