I think it may actually be from the 40's. Red, yellow & blue fabrics were very popular in the 40's. Possibly a combination of 30's & 40's fabrics. As others have said, you could either piece a border... or you could appliqué the entire top to a piece of quality muslin to add stability.
I did a similar quilt in repro fabrics. I bound it in Moda "30's Yellow". I never thought that would work, but it really tied everything together. Many people consider yellow a neutral, so I guess that kind of makes sense.