If you embark on the journey to fit a one piece hop then I wish you well young man. I've been there. I feel your pain. Personally I would suggest maybe trying a genuine Marui 2 piece hop first. Failing that you have two choices for fitting a single piece unit; modify your lower receiver with a Dremel to remove the screw mounting points and make a cutout between the freont pin lugs to allow the hop to slide out with the upper OR buy a new receiver designed to work with a single piece hop. If you choose the first you run the risk of screwing it up and destroying your receiver. If you choose the second you risk running into a whole host of issues with incompatible parts (trust me on this - I speak from bitter experience). You could well be potentially better off just cutting your losses and getting a Combat Machine.
If you do decide that the manly path of spending more than is entirely sensible trying to get a cheap gun to shoot straight is the path for you, I am here to help. No, really.