I want to stitch in the ditch (SID) with a walking foot to quilt a quilt sandwich that has quilting cotton on top, warm and natural batting in middle, and high end flannel on the back.

I usually use Aurifil 50 wt and a 90/14 Topstitch needle to quilt. OK on this one?

I saw previous flannel post re: washing the flannel, cleaning machine during and after due to lint , basting around outside, etc.
Any other suggestions regarding needle, thread machine settings?
I will experiment but thought Id ask the collective of experienced and brilliant folks here.

Thanks