Stay with the base (INT+LOG) x3 then add the characters highest unmodified attribute.
I actually had the same idea!
But then figured you got enough freebies as is!
You want more knowledge, spend karma on it.

Now stop being greedy and build your character! :p
Oh, and one more thing: I'm allowing actual skills to be treated as knowledge skills too, within reason.
Eg: If you have Demolitions 5, you don't have to buy Knowledge, Explosives to be able to tell what might've caused that explosion, to know what amount of explosives to use or to distinguish C4 from Semtex. It also helps with knowing the right place to put a bomb, though here some knowledge about architecture, vehicles, engineering or whatever fits in the situation might help too.
With a decent pistols knowledge you don't need Firearms knowledge to know stuff about how pistols or revolvers work, what their difference is etc, but still don't know squat about shotguns.