This would be very heavy if you are to make it for a king size bed. Quilts are not bedspreads and don't usually go to the floor. Of coarse you could make it that big if you please. No rules here. I bought a summer weight spread and use my quilts on top of that. This works better than bed ruffles for me. If you are going to do your own quilting, I suggest you look up "quilt as you go" for one that big. It may be easier than quilting a king size on a regular machine.
Good luck and welcome to quilting. It is the best bug I have ever been bitten by.