Most custom ROMs for Xperia Pro are done based on the MK16i variant. To be true, there isn't any difference or any issues in that, only some of us (like myself, who are interested in the minute details) owning an MK16a would like the branding to be so, in custom ROMs as well. Here is a flashable zip which will basically mod build.prop file to change all instances of MK16i to MK16a. Thus, your MK16a device will say so even after flashing a custom ROM.
Installation Instructions
1. Download and copy zip file to SD card
2. Reboot into recovery
3. Choose install zip from SD card, select zip and flash .
4. Reboot!
Installation Instructions
1. Download and copy zip file to SD card
2. Reboot into recovery
3. Choose install zip from SD card, select zip and flash .
4. Reboot!