I just built a Big Stik 60 and if the 40 size is as fun as the 60, you're in for blast. My model came out nose heavy, even with the elevator servo mounted on the side of the fuse near the tail. I would suggest not gluing the vertical stab until you have the plane balanced. Build the model out till it's ready to fly. Then do a CG check with the vertical stab mounted in the fuse, but not glued in. You'll more than likely need to add a couple ounces of lead to the tail section. If so, glue the lead inside the fuse where the vertical stab will mount. This way you don't need to mount the lead on the exterior of the model. Recheck the CG and once it's balanced, then glue in the vertical stab.

Also, I would suggest adding tailwires from the vertical to horizontal stab. As someone else noted, I was told the area of the fuse in front of the horizontal stab is weak. So I epoxied two popsicle sticks inside the fuse in that general area before gluing in the vertical stab. If you can, go with more engine. I'm running a 90 2 stroke and I can tell you blasting off to "blue angels" vertical climb out from takeoff is the most fun you can have.