You should just change out the piston,rod and sleeve.
Once the engine warms up and there is expansion in the sleeve, you will loose a lot of compression.
I have tried to get by during races with pitted piston and sleeves, and even sanded the top of the pitson with 1500 wet/dry sand paper to remove some of the pitting, but I barely made it through the day. Plus you have the deep gouge in the side of the piston which will lose even more compression.
Looks like you made have lost the snap ring for the wrist pin.