but I want to use less shea butter and also maybe discount the water a little to make a harder bar.
Using less water doesn't make for harder bar, it just makes for less cure time due to having less water to evaporate, which is part of the curing process. The other part of curing is the difference between making moonshine and a smooth sipping whiskey. Running your current recipe through SoapCalc, looks like you are using close to a 28% Lye Concentration...I use between 33% and 35% depending on the time of the year; I know some folks who use a 40% Lye Concentration.
The less Hard Oils/Butters you use, the softer your soap and the longer your cure time. Think about it...Castille Soap, which is 100% Olive Oil, with an average 33% Lye Solution, takes a good year to produce a hard bar. I use 40% Soft Oils, 60% Hard Oils and 5% SuperFat and get a nice hard bar at 6 weeks.
Recommendation I would make...drop your Castor Oil to 5%, Olive Oil to 45%, Shea Butter to 15% and then look for another 'hard' oil/butter like Palm Oil, Palm Kernel Flakes, Cocoa Butter, Lard or Tallow for the other 15%.
You can also reduce your SuperFat to zero or 2%.
ETA: There really isn't such a thing as a water "discount". By using less water than what your recipe calls for, all you are doing is increasing the strength of your Lye Concentration. As an example, if I use 10% less water, my Lye Concentration goes from 33% to almost 36%.