Default Downgrade from kitkat

I have a vs980 that I want to downgrade. Currently I'm on rooted 24a and I want to go to 12b. Do I simply flash the rooted 12b rom and 12b radios? Or do I need to follow the "Back to Stock" thread and flash the 11a rom via the lg tool? I've read about and flashed a "bootstack" and don't think either of those would downgrade that.

I'm nervous about downgrading because I went though hell recently trying to upgrade from 12b to 24a. After flashing paranoidandroid kitkat rom and 24a radios I was disconnected from verizons data network for a couple of days. I tried everything and ended up on verizon's rooted 24a without data connectivity. I thought the sim was corrupt but was on vacation and couldn't go to a verizon store. Weirdly, after a few days, it simply started working.

I had a lot of charging issues on verizon's 12b with various custom kernels and decided to flash 24a - only to find out that flash is mostly broken on it. I want to flash to rooted 12b and this time not use custom kernels.

Thanks for your help.
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