Kojunho, you are reading the chart incorrectly
The table you posted shows subnote (1) for circuit breakers
"Consult factory for circuit breaker applications"
Subnote (2) for Time delay Fuses recommends 60Amp fuses.
Subnote (3), which is the one that you keep referring to, is not for circuit breakers, it's for Normal Operating (non delay) Fuses, and is where you are getting your 80 Amp figure from.
Simply put, a welder with a 54 amp load will not work reliably, when turned up, on a 40 Amp breaker. A 60 Amp time delay fuse will not serve any purpose whatsoever when fed with a 40 Amp breaker.
You should call Miller, see what they recommend for a circuit breaker size, and then follow their instructions.
The same goes for the conductor sizing.
