Yep, I'd agree with what Jason said.
When I ran V3>702/722, I did as Jason suggested and ran line in at -5db. There has been discussion and conjecture whether using the line in attenuation on the 702 degrades the signal at all, but I don't think anyone has really tested and evaluated it. Personally, I just liked the simplicity of it, and I often ran a backup recording digital out of the V3 and didn't want to run that at lower gain.
If you do this -- line in at -5db -- your levels on the 702 will match your levels on the V3. To set it up this way, you need to go to the 702 menu item for use front panel knobs or use sensitivity settings, and then choose sensitivity settings. Then you need to go to the menu item that allows you to add gain or attenuate the line in settings, and set it for -5db (5db of attenuation).
At this point, you can run your V3 where you are most comfortable. I generally run for peaks hitting most often at about -6db, and usually this will give me actually peaks during the whole set of about -3db or -2db. Of course, it probably makes sense to run it cooler, but I have a hard time of unlearning old tricks of running things really hot (from my 16bit DAT days).