What is it?
It looks to me like a CVA (Connecticut Valley Arms) pistol kit. I have one I bought 35 years ago, still on the project list. CVA was bought by someone that Mr. Google can find for you. parts are likely available.
"Figure Out What You Believe and STAND YOUR GROUND!"
Nemo Me Impune Lacessit
Lots of Cast Iron to Cook With...
and a few defensive firearms, too!