The subordinate clause "From the way..." I understand the meaning of, however the main clause's meaning I do not. Would, if rephrased as, "I wouldn't wonder this time but what he [would die from]", be meaningfully equivalent to the below quote?
"From the way he cut up the other time you went away, I wouldn't wonder this time but what he died."
This is almost incomprehensible to a speaker of Modern English, who would probably guess it meant "I wouldn't be surprised if he died."
However, this is not quite accurate and it is best to understand but what and but that as an idiom in which the that/what can be ignored:
- After various verbs in negative or interrogative constructions, reversing the effect of the negative or interrogative so as to affirm more emphatically the dependent clause (e.g. I don't know but she's got notions into her head = ‘I think it likely that she's got notions into her head’). Frequently in but that.
"From the way he cut up the other time you went away, I think it is likely that he will die.”