Here is my experience with .125 overbore in a 250 block:
I built a stroker twice with .125 overbore. Both used 383 (common SBC stroker) pistons, 4.062 stroke crank, 5.7 inch inline rods. First time no block fill, second time filled about 1/2 way up except in front around the pump, same block both builds. I had trouble with overheating and clearly there was some block distortion based on bore wear patterns. I agree with above comments.
If you want to play with .125 over go for it. I recommend a sonic check on cylinder wall thickness. As a reference point my current stroker is at .060 over bore. There is one small dime-sized spot (back wall cylinder one down low) that sonic checked .070, no other spot thinner than about .125 or so. Thrust walls were all at least .200. It's been fine so far.
