I wash my 1960s quilts in warm water on gentle after a soak in the washer, but they are quilted and finished. If you don't wanto to finish this one first, then you'll need to baste it to a sheet on every sashing strip and all the edges. It would be a shame to have such beautiful work become a ball of strings.
After the wash cycle is done, I respin the quilt on a normal speed, but I would never agitate it at normal. Then a short tiime in the dryer and, finally, spread out to finish drying.