yankphan,
I also read 13" props were biggest untill i put a couple on, way to small for the 20cc's. yes, stock landing gear used, might replace them with retracts some day.
Not using twin sync, nthing fancy at all, have both engines on one channel mechanicaly adjusted to run together which they both do very well, Gas engines are very reliable set up properly. Nose weight is 0.8 kilos about 1.7 lbs with the CG at 4 3/4" felt good in the air...
I replaced most of the hardware with Dubro 4-40 including the pull pull cables... if you need any info as you build just ask, happy to help...