When I make a CW reproduction quilt, I'm a purist and want only reproductions from prior to around 1870 in there, with the exception of current muslins. Then that quilt becomes (for me) a record of the fabrics of that time.

I am working on a quilt with 1930's repros right now. I added some Moda solids in with the repros & I think I even grabbed one or two of the Downton Abbey fabrics (1920's repro). It's your quilt, make it what you want. If you want something that truly reflects a period piece quilt, then you want to stick with either repros or something very close to a repro. If you're just trying to make a beautiful quilt, there are plenty of examples of mixing old repros (including Civil War fabrics) with ultra modern fabrics & that looks really cool, too.

I have done a few quilt tops using Civil wars. For these I used only Civil wars and did not mix in other designs. such as batiks.