I put the OS 46 in mine & had the same issue. here's what I did. I cut a hole in the side of the fuse so I could turn the needle sideways because it got the screws out of the way & let it slide back to where it was about 1/8" off of the motor mount back.
It still makes the motor stick out a little more than the plans but it doesn't seem to bother mine & you'll also find that you need to add some nose weight if you use the 2-56 wires & the tail feather support wires. ( I had to add 3 oz. in the nose). I also had to shove my battery pack all the way under the fuel tank against the firewall so make sure you have enough room under there.

I took a couple pictures for you.

BTW, everythings looking good so far!!