The Rochester PowerJet was a transition (and not a very good one) from the early Rochester (1949, 1950) type AA (horrible), the 1951 BB (terrible, but better than horrible) and the 2G series which began in 1955 on smaller engines (wonderful). From memory (often a bad idea), the Powerjet was used only on some models of the 1955 and 1956 Oldsmobile on the 324.
In 45 years, I can remember selling maybe 3 rebuilding kits and zero of these carburetors.
(Opinion) if it is clean it makes a good doorstop (even if someone gave it to you).

Be very careful about kits. Yes, we do make them, and ours fit; but since Rochester referred to these as 2GC carburetors, some think the more conventional 2GC kits will fit, and they will not. The 2GC main metering jets will interchange; the power jets will not. And everything else (except perhaps body screws) is different.
(Opinion) MUCH better carburetors exist.
Probably the one saving grace, if you are in to this type of thing: since the carb is so rare, probably not 1 in a thousand car enthusiasts have actually seen one; you could open the hood at car shows, and roll out the old "it's an experimental carb that slipped out the door, and was replaced by the dealer at the first service". There are lots of gullible people that actually believe this story!
Jon.