My mechanic sugest the same thing just hone out the block new rings keep old piston,s
But this is the A12 i that had the same problem ass the A14 in the car now.
Aftter i removed the piston both of my machanic had a look at all piston,s and the bore
And said thay still dident know y it was fouling nmb four plug. one said maby that bore had change shape maby oval. I would have take it to the their machine guy and he would mesure it