Spray starch or sizing or before cutting pin sheer type paper like wrapping tissue under the fabric, lots of pins on cut edges.
You can use rolled jersey around the neck and pockets
I look forwards to the replies you receive. I think it’s bargain I would have left in the shop
Made a very warm nightgown out of it.
For a gown, I would trim those seams down to about 1/8" and do an overlock stitch down them. Congrats on the bargain.