Optimal Placement of Cleats
I am transitioning from mountain bike shoes to road bike shoes. A marked difference is the limitation of versatility in cleat placement. I prefer to have my cleat as far up and to the inner side of my foot as possible - pretty much at the balls of my feet. 


Typical road shoes use three bolts holes, with the positions of those holes being static (as opposed to mountain bike that have two bolt pattern in a slot that allows for forward/aft changes). In a road setup the ability to adjust cleat position (forward/aft or inboard/outboard) comes from the design of the cleat itself.  Some brands and systems offer a lot range in this regards while other less. In addition, road pedals themselves often come with different length axles which will help you fine tune the inboard/outboard position your foot (what you have been doing by shifting the cleat inboard on your mountain bike pedal and shoes). Finally, road bikes also tend to have a narrower stance (distance from the center-line to pedal; often termed the "Q-factor") relative to mountain bikes, meaning that all else being equal your feet will already be positioned closer to the center-line of the bike (relative to your mountain bike) before you even start tweaking your setup.

The take-home is that to get the same stance (distance from the center-line of the bike to the middle of your foot) the road cleat will be in a different inboard position relative to a mountain bike cleat position, so land-marking the mountain bike cleat position will not help you to get into the same final stance.  Unless you are very good with measuring these types of distances you may need to start over fresh when setting up your road cleat position.  


  It feels weird to have the cleat so centered on my foot. I feel like I can't use my calves as strategically now. Is this because it's more efficient to have the cleat central to the foot? 


Finally, the current "thinking" for fore/aft position cleat position is to have the pedal axle between your first and fifth metatarsal, that is, just behind the "ball of your foot (which is the first metatarsal). This keeps your calves muscles more neutral (requiring them to work less), reducing fatigue and oxygen consumption. The calve muscles  primarily play a postural role in cycling rather than generating any substantial power. If you are looking to generate more power, you should look into getting muscle recruitment from other muscle groups such as your glutes.