http://androidforums.com/spectrum-all-things-root/695380-spectrum-ota-blocker.html
You mean that OTA blocker?
I doubt there's much that can be done to really change a whole lot with these roms tbh. Maybe... MAYBE... you could replace the kernel with an updated one, but you'd likely have to modify a bit of stuff to get it to work right since some of the device paths I believe changed.
The reason GB was so much smoother and better on battery life is that with GB a phone was still intended to be a phone. With ICS/JB, a phone is intended to be more of a mini tablet that makes phone calls. Basically, there's more stuff going on with ICS/JB than there was on GB imo.
IF the source for, I think CM7, was available people could likely roll out GB based CM roms. But even that I'd bet will be a good bit of work to make happen. I doubt too many people would be interested to sink those kinds of man hours into a retro project on an outdated phone for a handful of people.