Well, you definitely don't want to modify the 230's engine to put out that kind of power, because it turns into a REAL money pit and performance parts are pretty scarce.
The Z400's engine is a bit tall, you'll have to drop the frame a tad or angle the engine forward more.
I have checked the frame to see if a radiator would fit, and there's also enough room for an oil tank and standard size battery as well.
The LT230E already has a battery box located in front of the grab bar and underneath the seat.
It's all relative to how much time and money you want in an LT230....it'll be a hell of a 230, no doubt it would be fun and great on trails, but you may be better off finding a quad that fits your wife better.
The Z400 is my wife's ride, and she really likes it.
She seems to control it well, especially considering she's only 110lbs.