I'll play devil's advocate, things to ponder. Wood is very open pored, possibly American walnut. Not likely his wood of choice. Hard to see the grain direction through the grip but less than ideal would be another factor. Checkering is crude and unevenly spaced. Military butt plate, mlitary cross bolts. What does the internal inletting look like- well fit to all the metal or just the edges.
I'm no expert, never even held one in my hands but reading Micheal's books suggests Seymour Griffin only created 1 quality of rifle, best. That said with a little work and elbow grease it could be a very nice little sporter.