DaveBoltman's answer is very remarkable and useful. However, the phosphors' wavelengths in Wikipedia are not exact. There are other references and Google books giving slightly different values. For instance, P1 w/l is 525, not 528 nm:
Anyway, I remember what colors those phosphors displayed (including the amber phosphors), so I am nearly sure of these RGB and Hex values:
I suppose that Apple //c and Apple /// monitors used the P24 GE phosphor, because they had its hue. And the background of the old monochrome CRTs usually was lighter than pure black, see this photo:
For better eye comfort, I suggest that the OP use any of those greens with that background. In the dark, the old-fashioned green on dark gray looks better than the present black on white.