Sounds like it will be a good combination. The 115 would have had you doing a lot more mods to increase strength. A couple thoughts. Reducing the span will not net any speed increase. Increasing wing loading means you would have to fly the wing at more positive angle of attack. That being said you can clip off the tips and replace them with something a bit less draggy. As far as incidence is concerned, I would set everything at zero. A good test is to trim the airplane for level flight at 1/2 throttle and then see what it does at full throttle. If it climbs then you are either nose heavy, have too much positive on the wing or both. This is all provided that the stab and engine are at zero to one another. On a sport airplane you could correct this with down thrust but that would be lost speed. Now the Jett. What muffler do,you have? If it's a Jett muffler there are 3 colors available gold, black and red. The different colors signify the different rpm they are tuned for. A call to Jett will verify what rpm muffler you have. You will want to prop for that rpm. The .76 is not a high rpm engine so if you can get an 11x8 or 11x9 in the rpm range all the better. I'm thinking the .76 May be happiest in the 13k to 14k range. Running anything less then 11" dia will be fruitless on that airframe. If running a pipe you may be able to go long and get enough to run a 11x10 or 11x11.