Post Possible way to downgrade from MK8 base to a MJx?

Hi to everyone, my question is if i can downgrade from a mk base to a mj base, the reason is i want the newest modem (MK8) right know, but i have a rom from sat with 4 files + pit that is very usefull to me, (is a MJ7 Base ROM)..the thing is if i am on a mk8 base and y try to flash the mj7 five files with odin, odin will FAIL to me? Thank you very much to everyone i love this comunity!

- Ive posted this in the Troubheshooting & Help thread, i apologize because i didn't know were to post it from the beggining