Your location is California. Is that the "home" of this rifle? If it is, I'd keep it bone stock. You unfortunately have to deal with state law on top of 922(r).
Buy some stripper clips and do some practicing. I'd also buy some 7.62x39 snap caps and put those on the stripper clips so they're the top 2 rounds loaded. It takes some of the fear out of a sloppy reload when you're getting used to using the stripper clips. I'm a big fan of the Tapco 20 rounders, but in order to convert my Yugo, I also had to change the stock and I removed the grenade launcher, bayonet, etc. From what I understand of California law, that configuration wouldn't be legal.
Also, Murray's firing pins are nice, but not needed. Your Yugo, like most, probably went through several years of war with the plain old free floating FP just fine. I had issues with mine until I stopped using Wolf ammo. With Brown Bear or Golden Tiger, I stopped getting popped primers (and a bent firing pin once).