Kekimus is alot of mana if you can constantly feed it cake. The Gourmaryllis is another good thing, if you have something that is very saturating and nourshing, for instance meat ingots from MFR. Now, with meat ignots you need to time it to drop every 5 seconds for gourmaryiliss. You are going to need a lot of food to keep up, and likely a gaia mana spreader too, depending on setup. The bug bear is cake isn't the easiest thing in the world to automate making, due to all the parts, but the flower is much simpler to automate.
I'd highly recommend getting at least Eleven Mana spreaders though, or even Gaia considering you want MASSIVE amounts of mana gen.