enlarging lenses are designed for specific magnification ranges. APOs are optimized for large magnification ratios and may not be stellar performers at 3-5X. Most 6 el. 50mm enlarging lenses are optimized at 8-10X, APOs somewhat higher. Four element lenses are usually optimized for 4-6X.
At 3X in your application, I think the $$$ would be better spent in another area.