AM, you really need to start doing a bit of thinking if you plan on staying in the hobby. Did you even notice the lead weight in the nose of your plane?? Put your thinking cap on, what does that tell you to do?? Just from the photo I can see the rails are wood, doesn't that give you any food for thought.
Look at the first photo of the fire wall, it's made of wood like your rails. Think about it. I took a bunch of photos of a set up I'm doing right now. I first read up on this plane, it comes out nose heavy so I installed the elevator servo and control rod in the back as far as I could. Then I installed the rudder servo right in front of the stab and installed a pull/pull control system. The only servo located where the ARF manufacture had a tray is the throttle servo. I studied then assembled and thought ahead.
The nose of your plane is just wood, something done all the time is cutting the cheeks off the nose so the fire wall is flush and using a normal motor mount like a GP adjustable.
No, if the mount has been used before you don't toss it, you can relocate the holes for another engine. The mount I'm using has been drilled three times. Do a bit of thinking and the answers to your problems will come to you. Think out of the box a little, it's your plane, you can do anything to it you like. That's what I was told.
There is s sticky that has everything you need to know in it for beginners