Hi ,I went to here for searching the reference of T430 2349's VGA port support for my Mavericks.
just would like to share something here from my experience after reading your pursuing:
1. install on MBR disk for multi boot of win7 and Mountain lion . in win7, install easyboot boot loader to start either WIN7 or MAC.
I repackaged the default Easyboot ISO file to append my T430 required drivers.
2. install Macericks on GPT partitioned external USB USB DISK/thumbdrive, since mavericks doesn't support MBR disk installation, but if you managed to copy everything of Mevericks from external to internal MBR disk, also got MBR mountain lion bootable, you should be able to load Mecericks from MBR as well. but I haven't tested this. I just noticed my mountain lion boot loader also can boot mevericks .
additionally, you don't need to disable virtualization in BIOS, if you need to use virtual box to create 64bit windows 7 running in mountain lion or mavericks. just use chameleon boot kernel flag: dart=0