That is what it looks like to me also.
Yes you can swap out the ejector for a 91 ejector.
I cross checked the part number and it came back as a HK 93 PSG1 pack.
So you will need the shoe and selector for it also.
I have not seen them at this price in about 5 or 6 years.
CDNN had them for 399.00 a long time back.