My vote is for a complete rebuild.
Here's why, looks like that piston says "010" on top so we know it's already been bored out once. You said that there was "silvery powder in the pan", that and the scoring leads me to believe that who ever rebuilt this engine didn't wash it out after having it machined.
So now you have that those fine metal particles in the bearings, in the connecting rod and crank shaft, up on your cam shaft, etc. causing premature wear.
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128 X 2, 129, 149, 1250, 1450 x 2
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