Apologies MIRKOSOFT, the file KICKUP.M65 file is not needed. I listed it in error as it is one of the files that is looked for as the system boots.
The only bitstream file I have is ddr20150928.bit so I have not tried any other combinations.
My SD card has the following files copied to it in the order listed below:
Older bitstreams require the additional files to have the extension G65 where the new ones are M65. Similarly the older files have the name C65GS where the newer ones are named MEGA65 etc.
I've been able to boot both the 910111 and 911001 ROMs from zimmers.net.