In the end you have done the correct methods to complete the airframe. If you are flying Sportsman, Intermediate or Advanced class a set of (2) 5S 4300 - 4500 25-30C lipos will complete the entire schedule. Early on I used 5S, 4400 Thunder Power , 25C rating. These weighed in at 520 grams = 1,040 in total, plenty of power to spare.
Changing from stainless to aluminum turnbuckles will gain you nothing in the end, the rods are too short to make any difference.
Keep the questions coming
Mike