I think that beyond #85 it will be very difficult to recover the private key, even with 1 TB of RAM (with the Baby-Giant Step algorithm).

With my 32 GB finding the #70 is already a hard task.

But there are other algorithms more suitable that don't need so much ram.

If the aim of this puzzle transaction has been to test the sha256 cracking power, now the challenge is cracking the elliptic curve relationship between private and public key.