Lots of shotguns...
I think I would add a Browning BPS.
When I started out, I had bought a 20ga shotgun for small game hunting. I later sold it as my post college life made small game hunting difficult. My intention was (and still is) to buy another sporting shotgun when the need develops. I bought a 12 ga Remigton M870 Police shotgun for "home defense". I think I shot that gun a total of five times in 15 years. But, it's there should I need it.
The black rifle suggestion is reasonable as one to acquire in the future. The Mini-14 actually handles that role pretty well as they are very reliable, but not a good what I would call much of a precision shooter. That's okay. They fulfill their designed role quite well in my opinion. I have one. I have owned other EBR's, but I am unwilling to feed them properly and hence sold them. No regrets.
As far as future acquisitions, I would look at a varmint rifle and perhaps another 30-caliber (ish) hunting rifle in a non-magnum caliber. But you so have the Marling 30-30 (Model 336 I presume) and the Remignton 7600 30-06.
I would also look at buying a higher end 22 rifle such as a CZ 452/453/455, perhaps a lever action 22 such as a older Marlin 39A or one of the Henry's, and a Ruger 10-22.
You have to own a 10-22. It is just the way things are!
This statement is kind of like woods use knives.... you have to have a Kabar Becker BK-9. (I don't, but I do have a BK-7.)
If the military rifles appeal to you, I would look at a Garand or one of the older Mausers or Springfields (WWI or WWII vintage).
Jump into handguns when you are ready. But I would choose a good 22 first and then a carry gun that you can also use for home defense.
