Oh ya, and what I forgot to mention:
When I changed the bearing, I saw a lot of the same Nova parts in there. The R7 rod and the piston & sleeve looked pretty much exactly like my Beat 5.
The carbs are for sure the same. That's obvious but the Rex didn't have that extra tight head button and O-ring like my Beat 5.
And I finally just found one of my pics of my Rex out of the car.