You can find some of the older SDKs here.
If you install more recent compatible driver, I guess, you will be able to use newer SDKs as well. As you know, OpenCL header files support macros to control multiple version of APIs. So, one can select the intended API version compatible with their OpenCL runtime/driver as required. Also, during the clBuildProgram, you may need to pass -cl-std=CL1.1" to control the CL version according to your targeted device (for example, currently CL 1.2 is enabled by default).