Gary - CG is probably very similar to yours, I have 2 x LiFe 3000 2S rx batteries just slightly before the nose cone and turbine/landing gear battery's just at the very back at of tray below the cockpit. Your tank is installed, powered by a ACEx 190
When I get sometime I will put it on my Xicoy CG meter. On take off its probably slightly nose heavy but as your fuel tank drains and when switches to the 2 main tanks, after 5mins of scale flying I had over 70% remaining in both tanks which puts it right on the CG, I will increase to 6mins flight time and see how it feels, if I end up just slightly aft of the CG for landing for this jet that's OK. It seems to like the higher alpha landings with no issues, just got to keep on the power
As for the brakes I'm just using the AG63 brake/steering gyro and its tied into the Xicoy LGC13C landing controller set at 2amps, the gear is retracting is slower than I would like but the gear retracted fine using a 2S 7.4v Lipo. I would use a 9.9v but I'd hate to stress or burnout the retract motors. From the time your hit the retract switch until the gear doors are closed your looking at 30secs. It's fine, I can live with it as long as it's reliable
2 F-16XLs will be flying tomorrow so I am looking forward to it.