I just went out to the garage and measured my Saito 180 with J Tec mount as it was mounted before I cut the motor box. The distance from the from the front of the motor box to the front of the cowl is 6 1/8" (plus or minus 1/4inch depending how you adjust the cowl). It should be a perfect fit! The more I hear about your RCS 140 the more I think I should have gotten one instead of the RCS 180. The RCS 140 will be the same length as my Saito 180 with mount. With the Saito 180 I needed one strip of lead weight to balance with all three servos in the tail. Th RCS 140 is a little heavier than the Saito 180 so I am betting it will balance about perfect.