i used the same servos as you did. im believe the plane is a holman design. i got no plans when i bought it used. ive had it for years and done nothing with it until now. when i bought it i was told it flies great with a zenoah g 38. it will be 16 lbs in the air. everything i read is the cg is on the main spar, like you say. which is 5.75 inches back from the le. one guy had to put 2 lbs of weight in the tail to get the balance. i balance it at 4 inches back from the leading edge, but it just does not seem right.