I just re-installed the FtB launcher and Ultimate as a test (I run from Curse these days)... When you load and run Ultimate, a copy of Minecraft v1.4.7 is loaded and run according to the Minecraft opening screen itself, if you look in the lower left hand corner before selecting a world to play. Trying to run Ultimate on MC 1.7 will not work well because there have been too many internal changes to Minecraft and many of the mods were never updated.
If you want to run a 1.7 pack you need to look at the pack's description to find the MC version it uses. There are several newer packs that are attempts to recreate Ultimate. I believe the latest is "Resurrection" which even includes Gregtech, which was separated out in pack versions between Ultimate and now due to mod developer differences.