What about the Kel-Tec SU-16? Are those California legal? If so, you might add this to your list of options.
The Springfield M1A is a fine rifle. I have an early 1980's pre-ban NM M1A made with many USGI parts that I wouldn't consider trading or selling. Mine is super reliable and accurate. It does everything I could ask a rifle to do. But being full-size doesn't really make it well suited to home defense. If I considered an M1A for home defense purposes, I would seriously look at the Scout or Bush versions with the shorter barrels. The new ones seem to be just as reliable and accurate, but most of the military parts have dried up and I hear many of the newer guns aren't as durable as the old ones. I assume this has something to do with using cast parts instead of forged ones. I have never owned a recent M1A so I can't say how good they really are. Nevertheless I would strongly consider looking at one of these and asking around about them before buying. They are expensive and the 10 rd Springfield Armory factory mags are rather pricey too. So make sure you feel confident in the weapon before buying it.
For .308 ammo, the 155 gr Hornady AMAX loads seem to work VERY well. They fragment dramatically, creating a more severe wound than the best .223 while offering optimal penetration. These are hard to find now commercially, but if you reload you can get the bullets easily and load your own. Otherwise, the Winchester 150 gr Supreme Ballistic Silvertip, Federal Premium 150 gr Nosler Ballistic Tip or the Black Hills Gold 150 gr Nosler Ballistic Tips should all be excellent choices for defensive ammo.
I would advise you steer clear of the Mini-14 if at all possible. I do own one of these and I keep it for plinking and because I understand it's limitations. With proper magazines, the Ruger Mini-14 can be as reliable as any semi-auto made. But finding good magazines is very difficult. Ruger only makes factory 5 rounders now for civilians. Other than these, the only thing I have heard of that's even close to reliable are the Pro-Mag 10 rounders (that actually only seem to work right with 9 rounds). It seems these rifles also have quite a bit of difference in how the mags fit. I have seen some Mini's that aren't exactly friendly when it comes to mag insertion. Mine seems to accept any mag I have tried. But I have a friend with one that looks identical to mine that will not accept most of my hi-caps! I cannot understand this. On top of this, the Mini really isn't very accurate. At CQB distance it will more than suffice, but after you use it in other ways, you will likely find yourself disappointed in the gun. So unless you can't do any better, I would avoid this gun.
You might also look around and see if there are any AK variants that are CA legal. I know there are a couple of types on the market that only accept 10 round single stack mags. And Saiga may make a model that only uses limited capacity mags as well. The Saiga also is without the pistol grip, so this might be another option.
Another carbine-rifle worth considering are the Marlin lever guns. Since you are gonna be limited in ammo capacity anyway, I really would not consider one of these guns as a disadvantage. They are durable, reliable, handy and come in many hard hitting calibers. They are also more politically correct. This same basic design has graced nearly every western ever made. Hunters use them by the thousands. Therefore they don't terrify soccer moms quite as bad as some other designs. One excellent example is Marlin's 1895 Guide Guns. Or if you wish you could get a .44 Magnum, 30-30, .35 Remington, 444 Marlin, and various other calibers. Even the full-size 20" rifles can be customized by a good gunsmith, and you can have the barrel taken down to 18" or even 16.5" or so, if you wish. Off course ghost ring sights can be added as well as various other things. And you can even get them in a stainless finish! If you would like a picture of one of these, IM me your email address and I will send you one. I think you would find this gun to your liking. I also think you will not have to worry about poor terminal performance with a 45-70 at your disposal! If this causes an over-penetration fear, a 30-30 with 125 gr Federal HP's may be the best way to go.
And before I close, let me apologize for any poor grammar, incoherent thoughts or rambling, as it is very late and I am half asleep as I type this. LOL.
-Charging Handle