Although the plane will fly fine "as is", a few mods can make it fly better. I agree with Kiwi in making the stab thicker and wider and longer (stronger, less flexing, more area). I would, also, increase the tail moment if I am going to increase the area. Butt joint a 2 inch piece of balsa to the back of the fuselage and move the stab back accordingly. The stab will hold things together and you don't need any other reinforcement. Bring the motor mounts all the way back to the wing, and use 1/16 inch Birch doublerson each side at least back as far as the middle of the wing, and I would bring them back as far as a couple of inches behind the wing, bringing it to a point, or rounding it so that you don't leave a shear point for the fuselage to break at this spot. A total tail area of 22 to 23% of the wing area would be good, although this is always a point of difference. I would not recess the tank. It weakens the nose and does not allow for adjustment up and down. You need to add an adjustable tank mount, adjustable leadout guide and adjustable tip weight. There are a number of variations of these and it becomes your choice.
As to power, we built one using our modified 35 and 40 FP for power turning a 12 x 6 BY&O prop. No problem, and it flew thrugh the wind. Just remember, power does not mean you are flying faster. You use pitch to determine lap speed, diameter for thrust. It is like the large tires used on a dragster. You need traction to pull through the wind. Of cocurse, you can get too big a prop and reach a point where the prop stops and the wing turns (a little extreme). But we have never found a 12 inch prop on a 48 inch wing to be excessive--especially when you are running it slow. As such, I would opt for the 40H over the Enya. The weight will be the same, but you will have more power (and probably turn an 11 inch prop with this one.)
If you have heavy wood or warped wood, replace it while you are building the plane. Heavy planes are called "Bowser".