The font SP uses (Gorton Modified) doesn't have an electronic version. It's a bit like Arial, Helvetica and Engraver's Gothic fonts, with different bits from each. The "G" from Arial, the "Q" from Engraver's Gothic, etc, but some characters are not like any of them ("*" for example).
I believe the Keyboard Layout Editor uses Engraver's Gothic for SA sets. You can see in particular the "&" character doesn't match, among others, and it doesn't allow you to make the text size as large as they actually appear on the real thing. Another flaw in KLE is the colour matching. It uses the correct colour for the base of the keycap, but the keytop is lightened, so the colours in the mockup appear lighter than they really are, but I see you've used actual scans of the colour ring samples, which should give a slightly better representation. I find these to be the most accurate, even though they're still not perfect (and NN is missing):
http://deskthority.net/wiki/Signature_Plastics_ABS_coloursIf you're planning on using fully sculptured SA profile, you should be aware that SP doesn't have Row 4 Shift moulds yet (we've been pushing them to make them) for the 2.25x and 2.75x Shift keys. All Row 3 SA profile is not affected by this issue, of course.
Anyway, I really like the colourway on this keyset, it reminds me of Penumbra (which is still my all-time favourite set)