How LARGE are you printing?
If you are not printing a 35mm frame at larger than 11x14, and maybe larger than 16x20, don't worry about the "optimal" aperture of the lens. The practical side is, unless you use a magnifier and look at a very detailed image up close, you likely won't see the difference anyway.
To prove this theory, make a print at your expected print size at both the "optimal" aperture and at f/16 (the smallest aperture on the EL-Nikkor 50/2.8) and see if you can see a difference in the images. I would guess that you will not see a difference.
Also if you are doing that detailed work, you would have to use a glass carrier to make sure that the negative is FLAT and not bowed, and you would have to make sure that your enlarger is in alignment on all 3 planes (easel, negative, lens).
Light = heat.
That is why negatives sometimes pop/warp when you are printing them.