Have you tried hashcat yet?
Wish you find your coins, good luck.
I've spent close to 250k since 2014 on this, so, yes.
Bruteforcing is no option.
Dave succesfully recovered a wallet holding +- 1800
BTC around the same time (lost all passwords the same day), so i know he's a capable guy.
If he tells me after almost ten years it's impossible using the bruteforce technique, then i trust him.
I guess i'll wait it out until our technology evolves.
So who's this mighty Dave Guy?
I guess he must be very conversant with the password utils more than the private keys utils that we are handy with. But we will definitely say you should never let your gourd down because you still have hopes and you could just have a dream and remember what your forgotten password was... but unlike the private key operation, you can wake up from a dream remembering all 64 hexadecimal character private key or 51/52 compressed or uncompressed format of your private key... except you wrote it down somewhere or backed it up somehow.
Best we leave this for Dave to handle and maybe someday when we have the private keys backed up with passwords for stronger security against theft when the EC curve has been defeated... maybe until then will we be able to ask for Dave's assistance but right now... 66 bits is slapping our faces mercilessly that we don't know a way to tackle it...