Congratulations to the solver of puzzle 67, I saw that the solver uses MARA Slipstream. Is good to know that MARA works well for lower range puzzles 

Puzzle 67 - 1BY8GQbnueYofwSuFAT3USAhGjPrkxDdW9
00000000000000000000000000000000000000000000000730fc235c1942c1ae
KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qbP2K5cm35XKMND1X1KW

We just won BTC67 challenge and earned 6.7 BTC!

We had to check roughly 42 058 576 Trillion private keys before finding it (57% of the possibilities)
It took us (ironically) 67 days

Cheers to @ProofOfDuck for the statistical modeling!
Cheers to everyone who saw an opportunity and helped me fund this thing.

BTC68 Here we come!