Is there a reason to replace with another fluorescent fixture? I have been reading about the LED lights now available - use a lot less battery and have a decent "color" to the light. I know you want a good light over the galley, but are you sure the fluorescent is the best choice?
On the subject of quality of light, I recently bought new "warm white" 12" flourescent tubes from Amazon, for the remarkably reasonable price of $3.24 each, including shipping.
The light temperature is about the same as an incandescent, very pleasant.
I should really start a business selling these as "marine" tubes for $50 each.
BTW, when buying flourescent tubes AND LEDs, the term "warm white" is thrown around with abandon. However, the actual colour temp. is harder to lie about and is usually a fair measure of light quality. An incandescent is 2700F, and anything up to 3200F is pretty warm. I have LEDs that are 3150, and these tubes are 3000. The light from both is fine.
You see some LED products out there that are 5000F, which is very cold, still described as "warm white".