I did this upgrade and was pleased with the results. You will need to replace the cutlass bearing(the 7/8 bearing has the same OD as the 3/4), ream out the shaft log tube a bit to increase the clearance, and bore out the stuffing box to the larger diameter, and of course put in new packing of the correct size. None of this was particularly difficult. I opted to keep my existing propellor, so the shaft had to be machined to accept the 3/4 diameter taper. It probably would be better to go with a new prop hub with a 7/8 taper, but this did work OK for me.
