Depends what data rates you need. The 7731 bridge is the only way to do this effectively for high throughput. The 7761 can mesh - use the sector model - 7761S. Depending on how noisy the 2,4GHz environment is you may wish to consider a move to 5GHz - If you do I'd suggest looking at the appropriate antenna for that.
None of the 802.11ac products can mesh yet - which means the T300 is out at the moment even though it has 2.4GHz radios in it. (2.4GHz giving longer range than 5.0GHz and ac being only a 5GHz technology).
I believe the next revision of firmware will enable meshing which is overdue.
It will create a 3D map of your Root and Mesh APs. You can click on either node, and then the Mesh Info tab, to check and see if both APs have sufficient RSSI. This is similar to what TSEs can pull from your ZD debug with internal (Merlin) tool. In this case, this AP, can see AP_1F:E5:10 at RSSI of 27 on channel 157, so is a good mesh candidate.
AP: c4:10:8a:1f:cc:60 / 10.10.1.11 / fc00::1 Name : AP2 Mesh Role : ROOT AP
Neighbor MAC rssi/radio ch state adv depth reason last seen c4:10:8a:1f:c6:10 13/11g/n 1 0 0 Tue Jul 8 01:31:11 2014 c4:10:8a:1f:be:00 27/11g/n 1 0 0 Tue Jul 8 01:09:11 2014 c4:10:8a:20:8d:c0 29/11g/n 8 0 0 Tue Jul 8 01:27:11 2014 c4:10:8a:1f:e5:10 27/11a/n 157 D 1 1 c Tue Jul 8 01:35:34 2014