I took my Lisa Surfer apart last night to begin my hop-up. Here is what I found and did: First, it appears that the new Lisa Surfer has a plastic steering fin. It sounded to me like in the past, this fin was metal?.
It also has a plastic box which held the original electrics (not sure if the older ones had this or not). I will continue to use this box to hold the new electrics. Also, I painted all of my metal screws with clear rust proof acrylic paint and coated the seals and the screws with a thin layer of Vaseline (this should help the seal be more air tight and keep the water off).
Next, I found Lisa's head to be loose so I needed to glue this in place. I am now in the process of replacing the servo with a stock full size servo from a 27Mhz car radio and receiver. In order to install the new servo, I needed to cut off the thin plastic ridge servo holder where the front of the original servo sat because my new servo's servo arm was hitting this ridge. I then inserted the new servo and glued it in place with 5 minute epoxy and replaced the plastic retaining bar back over this with the original screws.
Now on to the motor: The stock motor has a male hex coupler on the motor shaft end which then fits into a female hex adapter on the propeller shaft end. I intend to replace this motor with a 540 size brushless and an 18-25 amp ESC. This morning I did some Googling and found some hex adapters which may work (in place of the Graupner 3346 mentioned in a previous thread). Please, would someone look at these and see if they may work as a replacement. I'll try to attach some pictures of my progress once I figure out how to do this.
Here is the link for the motor coupler.