Nice ref Grendels. Scott I think I've read somewhere that the colour ILM used has now been discontinued (like most of the colours used on the models). For mine I used 25% humbrol 147 & 75% humbrol 28. But I do like the Falcon to have a 'creamy' shade to her (think blasting out of mos eisley). Some people however like much more grey so go 50/50 with the humbrol 147 & 28. I know theres other formulars out there like Tamiya white x4 and Deck Tan x1 (I might try a 50/50 mix of vallejo white with deck tan just out of interest) Iv also heard to use grime and reefer white 50/50. But Its really down to mixing up what you like. Hope Iv been of some help.
Heres my colour ref for the top & bottom:
Now please just use this as a guide, as you know different manufactures have different tones in colour. And this is from memory! Anyway good luck and get painting! ;D