This is the actual firearm you are bidding on. Parkerized finish, new barrel, barrel nut, and latch, front sight and folding stock. I think Century made more receivers than they had military surplus parts to complete. In any case, parts kits are still widely available for the home builder to work with for around $160. Century used an 8mm grip-to-receiver split-pin (the same as the military SMG) so your surplus grip will fit, but you must still have a block installed in the front of your surplus grip frame to stop the selector from moving fully forward to the full-auto position. The barrel trunnion is bored for the smaller diameter semi-auto barrels and the feed ramp is the semi-auto style with a ring to support the breech of the barrel. This is actually a more accurate and reliable set-up than the unsupported breech of SMG feed ramps.
Most important, this semi-auto receiver has the blocking bar welded inside the right rear wall which will obviously prevent a full auto bolt from recoiling inside the receiver. Semi-auto bolts, in addition to being adapted to closed-bolt/striker fired design, have a slot milled down the side so they could pass over the blocking bar. These receivers will accept the standard metal folding stock or wooden stock.