From The North American Review:
1. If this be the motive of the philanthropist, the economist will show him that he is making an unwise application of his money in giving it to a mendicant.
2. If this be the true explanation of the great service which the lower memory sometimes renders to eminent minds, it would follow that it is not by the direct cultivation of the memory, but rather by cultivating this cause of it that discipline can be useful.
What I learnt was, if a writer chooses the present subjunctive, it must be referring to the present, so the main clause has will, like sentence one, while would require the past subjunctive: were, never be; did I learn the wrong thing or does the writer make a grammatical mistake in sentence 2?
Thank you. Joe.
Pope of the Dictionary.com Forum
The second seems odd to me- were/would would be a more obvious pairing, though I too can't work out the meaning.
More context might help with #2, I agree, though, that "were/would" would be more natural than "be/would".