Vz.58 with underslung R870MCS. The M43 round has a good degree of stopping power for its size, presumably zombies won't be hoiking around any firepower of their own, so the range and precision of the NATO 7,62 round won't be worth the relatively limited amount of ordinance I would be able carry. The Masterkey gives a quick exit if things get a tad too hairy, and can be reassembled into a fullsize shotgun if, for whatever reason, the Vzor gives out, or if ammunition for it just becomes too scarce. (Now, if only they'd make one based on the R1100! >=) )
As for a sidearm, can't go wrong with a good 'ol machete. Sure, pistols are great for people who don't want to get their hands (too) dirty, but nothing sucks more than running out of ammo for the last weapon you've got on your person =\
(A lot of people would say, use a pistol, not a knife. I'd say, if you're in the sort of situation you need a pistol, you shouldn't be shooting, you should be running, and you can run faster without the ammo for a pistol, or the distraction of trying to reload it when the shit hits the fan. The only targets you need to concern yourself with are those that are within striking distance, and directly in your exit corridor. Besides, everyone knows you run faster with a knife ^^)
Guess people like pictures, so here's a Vzor 58: (it might look like an Kalashnikov, but don't let that fool you! If anything, this rifle is a descendant of the Bren gun!)
And here's the masterkey. It's designed to be used, as the name suggests, to open doors, but in a pinch, it'll give you the stopping power of a 12gauge. I'd say the lack of balance and smaller magazine capacity are a fair tradeoff for having it at hand whenever you've got your rifle ready.