I love vintage quilt tops, even when they are somewhat wonky. Sometimes their seams don't match and they will not lay flat for anything! They pose their own problems when considering the quilting plan.
Firstly, they tend to be fragile. This one has muslin you can almost read a book through! So I always do a full float on vintage tops. That is, I do not attach the top to any leaders. I load the back and backing and then lay down the top, smoothing it out and basting the edges down. That way, the top gets no undue pressure from stretching.
And often the individual blocks act independently. That yellow plaid butterfly appears to be lifting off the quilt. Luckily, tops of this era were traditionally quilted in loose, open designs. The meandering loops work perfectly here to ease in the fullness of the block. (Besides, I think it looks like the dizzying flight path of a butterfly.)
And now, here's that yellow butterfly all settled down and resting on the quilt top.
Speaking of vintage, look at some of these classic fabrics!
Don't be afraid to take a big step if one is indicated.
You can't cross a chasm in two small jumps.
David Lloyd George