An APO lens should not make a difference for B&W printing.
Graded paper is sensitive to blue light; variable-contrast to blue and green. Neither is sensitive to red, which is why safelights are red.
Non-APO lenses are corrected for blue and green, so the additional red correction provided by an APO lens is not needed.
I use Schneider Apo-Componon HM lenses for all my enlargements.
They're superb lenses, but as I said the APO correction is probably of no benefit for B&W work.
I only do B&W now, but I used to also do Cibachromes using an additive-light head, which is why I bought the APO lenses.
I think 40mm is a bit short for 35mm; I use 45mm.