Roaming between the Lightweight Access Point Protocol (LWAPP) and the non LWAPP access points (APs) is not supported due to the mobility tunnel in the LWAPP.
There is no way to obtain a clean handoff between the mesh APs and the autonomous APs. When connected to the mesh APs, traffic passes through an LWAPP tunnel. Since there is no mobility tunnel between the controller and the autonomous APs, the roam does not work properly.
Also, the client receives a different information element when on the mesh APs compared to the other APs. Since it uses the same service set identifier (SSID), it cannot understand what to do, which causes the client to lock up. So there is no roaming between different devices that use the same SSID. There is no support for this functionality.
So you can convert the Autonomous access points to Lightweight access points for roaming to work.
Note: AP 350 can never be converted to Lightweight access points.Not only that any AP with 802.11b radio alone cant be converted.
Refer to these documents for more information on converting 1200 APs