I have the 770 also and love it. I have it in my Horn Quilters Dream 3180, but it is not a perfect fit, however it works. You just can't lower it all the way to put the cover on, but I never do that anyway. Also the lift is a bit light, so when I embroider, I move the machine to the left so the left set of feet actually sit on the cabinet and not one the platform; then I don't have to worry about the module losing connection with the machine, which has happened to me in the past.
The 740 is not embroidery capable. Did you know there was a 720 available also? It has embroidery capabilities but is a 5.5mm feed dog machine instead of the 9mm.