Okay after a few boot headaches I managed to upgrade from 10.7 DSDT system to a 10.9.1 UEFI system. Here's what I did.
1. I prepared a 10.9 USB boot drive using unibeast
2. I updated my bios to UE1 using a bootable USB DOS Drive prepared from rufus and the downloaded bios from Gigabyte. There are a few videos online but basically you can't use any of the gigabyte bios tools like Qupdate or @Bios when upgrading to an UEFI bios from an F bios.
3. I upgraded my 10.7 install using the guide -
http://www.tonymacx86.com/374-unibeast-install-os-x-mavericks-any-supported-intel-based-pc.html
4. When I tried to reboot using the USB drive (per step 5), my install of 10.9 wouldn't load. I tried manually removing old kext's using terminal from the Mavericks install USB. I removed one at a time with no success and was about to give up when I noticed (using verbose loading) that the boot was loading custom DSDT's from my existing chimera setup. SO, I renamed /Extra on my 10.9 drive to /OldExtra and voila, the system booted.
5. I went ahead and updated to 10.9.1 using the app store and reboot again using the USB boot drive.
6. I installed Multibeast using the attached configuration file and rebooted again without the USB boot drive with no crashes so far.
I've rerun a benchmark score and things seem comparable. I'll do some testing but things look to be working quite well. Now I just need to manage all the update issues many face when upgrading Mac OS X, like incompatible software, etc...