BoneDoc, I mounted my engine inverted. Works good that way. It also helps on the lateral balance. Obviously you don't have the cylinder sticking out the side to make that side heavy. I'm sorry but I don't have a way to take a picture to show you my rudder servo. I think there are some earlier in this thread by Stratos. I did mine the same way he did. But what I did was to mount it on the opposite side of the elevator servo and the length of the servo further forward so they wouldn't hit. I just cut away the covering and glued, with 30 minutue epoxy, a brace on each side just wide enough to hold the servo mount. I glued my braces in vertically and made them long enough to capture all the wood on the fuse that I could. (top to bottom) I think the sticks I used were 1/4" square. I used spruce, not balsa. I was able to fit the stick in there by feeling from the elevator side opening as well as the freshly cut rudder opening. It really wasn't hard at all. I use another stick to wedge between each brace from the opposite side, which I didn't glue, just to hold it in place while the glue dried. Then I drilled the holes for the servo mounts with a 1/16" drill and mounted the servo. I had to patch an area above the servo with white covering just because I had the hole larger than it need to be. This is actually a very easy thing to do. I wish I could give you a picture, but I don't have the means. Anyways, it was easy and I like how it turned out. It'll really help your balance, especially with the 150. That engine will make this plane sing.
Thanks,
Barry