I have used two old robart valves, two servos and the Jomar sequencer for years on my F-4. The up assit cylinders will prevent the mains from unlocking unless you use some kind of restrictor. BV recommended using a wheel collar a hundred years ago when I built mine and that has worked perfectly for me. One note on the F-4 if one of your mains gets hung up on the gear door and it will happen from time to time you will notice the trim change. It's a great airplane.

David Reid