At the very least, you need to learn how to post a link to you sets to allow for viewing. ( Don't ask me how to. Because I don't know either )
You could make it easier by telling us which albums you made I checked the 1879 mint and proof sets, but there are no digital albums for those.
You have a GREAT 1879 set! I'm sure it took a lot of searching to find all of those coins, and the quality is outstanding! I once toyed with the idea of an 1879 set, although it would never have been as nice as yours. My avatar is an 1879 quarter that I bought in 1971, now in a first generation PCGS holder as MS65. Here are a couple (old) pics:
Do you think you'll ever add proof gold to your set?
Yes, that quarter was my favorite coin for many years. It cost $95 in 1971, which was a lot for a kid working his way through college. I've never sent any coins to CAC, but if I ever sell, I have many that should be CAC stickered.
Appearances of the1879 gold proofs in auctions are undoubtedly rare. I can understand your reluctance to purchase impaired proofs, when the rest of your set is high grade, but with pops of 6 to 14, they'll be pricey. I'd have to weigh completeness of the set against my desire for other coins. Whatever your decision, good luck!
Done! Comments left on that set and three showcases!