Ok so technically speaking it may have been possible to base58 the passphrase get a result then sha256 that result with a password (or am I missing something).
...
I'm not sure if you understand what you're talking about. Why would you Base58 a passphrase, whatever you mean by that passphrase.
Explain how would you SHA256(something) with a password!
Let me ask you, I know it's too late but it may serve educational value, why didn't you document what you have done in the past? It's not surprising that after a long time memory blurs and this is the reason why nobody should skip to document stuff, especially when you're doing something non-standard. I recommend to also document standard stuff because at some point of time someone will need this documentation, especially after a long time.
In many cases the concept of a brainwallet is sort of flawed when people SHA256(human_secret) and this "human_secret" has weak entropy, is something known like names, citations or song texts or whatever is already present online or is more or less easy to guess based on personal data e.g.
From a brainwallet you get a private key that is simply the SHA256(human_secret). If you want to secure this further, you could apply BIP38 and encrypt that private key with another passphrase (which needs to be documented separately and best with some decent redundancy, too). On the other hand a BIP38 encrypted private key has a recognizable form and shouldn't be misinterpreted.
You're in trouble now because you didn't seem to document anything and you and we have to guess, which may not lead to a straightforward solution, if at all.
