I think it is just silly to consider only Ruger 10/22's when shooting these buggers, even with bizarre 90 round triple clips. If they come in with any speed at all, and in large numbers, when they are close enough to hit with any .22, it could be problematic.
You need to reach out and touch them starting at six or seven hundred yards (marked with nice white stakes, just like in Zulu Dawn); preferably with semi-automatic weapons. This is precisely what the M-14 was designed for in the 1950's. Yes, it is a fairly large caliber-.308. But we seem to have dropped the whole mobility thing in favor of an 18th Century French model of pointed symmetry. We might consider saving space by using the shells over and over by getting bullets and powder and reloading gear (about which I know absolutely nothing).
Slings are essential, given the kick of this cartridge. First elongate the sling, then wrap it around the upper left arm. Then a full turn around the lower left arm. Nestle the stock in the right shoulder and adjust the sling for a tight fit with the left hand on the front stock. Your left arm, chest/shoulder, and the rifle are a triangular, solid, one piece unit. If you have a good rubber shock absorber at the end of the stock, then rapid, accurate, and prolonged fire is a real possibility.
Ideally, shooters should be in a sitting position with something upon which to rest, and stabilize, the rifle. Each shooter should have an assigned field of fire--so far to the left and so far to the right. These fields should overlap.
When the undead get within, say 250 yards, switch to a lighter caliber; there is a lot of .223 ammo out there, so an M-16 variant or a Ruger Mini-14 (perhaps with an accurized longer barrel). Again semi-automatic is best, but with a lesser kick, the sling might be dispensed with.
At 150 yds "Unleash Hell" (I had to use that) with the above-described Claymore-propelled Greek Fire. If they get within 50 yds, break out the 10/22's and hope the 90 rd clips are more manageable than they appear.
Let's hope it doesn't end up being a reenactment of Zulu Dawn.
Assuming you have at least knocked them all down, send a few folks out with .22 semi-auto pistols and put a round in each brain pan. (For the perfectionists.)
Move. If it doesn't smell really bad yet, it soon will. Or 'steal' a D-9 Caterpillar.