I have the exact same engine, a Fox Eagle IV, .74, in my Shoestring. Excellent performer. Has the Eagle IV late model, single needle carb. Has adjustable air bleed for low end. Very user friendly. I used 10% Cool Power for break in, and flying. I've got it mounted horizontaly using a Slimline Pitts muffler. You've made a good choice. I have had 4 of these Fox .74's at one time. I sold 3 of them off in excellent shape. The people in my club grabbed them because they knew that all of my engines run well.
Hope this helps. > Jim