boring out the 3S-GTE block

my bottom end's looking a bit tired... we've got the head off and it's showing some wear in cylinders 2 & 3. It's going to need new rings most likely but that just might not be enough...

Does anyone know how far the block can be bored out safely or how far is common? I don't want the walls to end up too thin or anything...

I might get it done and get some oversize JE pistons.

.020 over is the safest you are going to get.
Any boring is going to make cracking more risky.

thanks Jeff...this is turning out to be a monster job... my head was soft so i have to get hold of a new one of them as well....