Doing the math, you are about 41 feet into the bedrock. Setting the pump up 25 feet off the bottom gave you 25 feet of room for sediment to build up. Since we don't know what kind of bedrock you are in and where the water is entering the well (top/bottom fed?), it's hard to say what raising the pump up to the bottom of the casing will do. Anything higher than the bottom of the casing would just stir up any build up of sediment.
If it is top fed and the sediment builds up around the pump motor, you risk burning up the pump from lack of cooling. I would raise it up so the pump is in the casing. That way, water will flow past the motor for cooling. Can't say if it would help with the turbidity though.
Do you need the full GPM of the pump? Maybe you could choke it back with a flow restrictor or with a CSV. I know on my well, the faster I pump it, the more clay I bring up. I had to clear out the well twice because the bottom filled up with sediment.