I don't have an X70 or 702t, but I see the cam has no TC in. Wondering if it sends TC out on SDI that you could get a black box to strip off TC to send to the 702t which can chase external TC in reader mode. I thought AJA had such a box but I couldn't find it.
Depending on the video editing software you are using, you can also use a Lockit box for TC fed to the 702t and to your camera as an audio signal. Here's a workflow for BlackMagic using Resolve, pretty sure Avid will convert an audio channel to TC too. http://forum.blackmagicdesign.com/viewtopic.php?f=2&t=4849
I very much appreciate your input Steve. I guess something like the Ambient Recording ACL 204 - ACN Portable Timecode Synchronizer would do it. I also see there are wireless TC transceivers. I was hoping the X-70 would have an intrinsic TC clock. The budget won't stretch to all this, so it looks like I'll continue audio syncing FTTB.