Although there are many folks who are successful using their embroidery machines for quilting, I was never very successful. I had a problem supporting the quilt so there was no drag. Precise rehooping can also be a problem. I was using a Viking with a large embroidery area and the 5X7 embroidery field on the 770 will be a challenge. I did make several quilts using a quilt-as-you go technique, doing a block at a time then joining. I also did several table runners using an endless hoop and a specially digitized design, but the quilting was just in the border close to the edge.
You never know till you try, however. I would suggest start on something small like a table topper, then go on to a baby quilt. Should give you an idea if it's doable.