Just a Mechanical Engineer here, but I doubt that there would be any problem charging a large battery. After all, you only need to charge enough to replace the amount you used in starting. So whether the battery is small or large, the amount of charging needed is the same. The idea of a larger battery taking longer to charge is only valid if it was dischsrged farther.
In practical terms, if you are starting in a cold climate, more battery is better since you may need to crank longer to get started. In Southern California, even in winter, a group 24 starting battery is more than enough. If you have two battery banks, I suggest that you keep the starting battery sized reasonably and put the money in a larger house battery (deep cycle type). If you do run down the starting battery switching to the house battery is possible or, in the worst case, to "both".
A further suggestion. If you are not connected to shore power and a charger, I have found (on a mooring) that one of the small flexible solar panels tied to my boom does a great job of keeping both batteries fully charged. Just be sure to get the voltage regulator to go with it (they have versions for single or dual battery banks) or you will shorten your battery life.