Oh dear God! 318 stroker

Welcome.
Sentimental attachment to the block, okay. 340-349 c.i., period. You got your reasons, who am I to argue, if that's what you want?
As mentioned, I wouldn't stroke it. Too many custom ($$$$) and discontinued parts involved. Have it sonic checked and see if it'll go to 4.040, some early and truck blocks will. You wouldn't be the first person to build a 340 out of a 318. And it'll all be common, off the shelf parts. If it won't go 4.040 and you still want to keep the block, sleeve it and get your bore. Sleeving 8 holes and using standard parts is easier and cheaper than custom pistons and offset grinding cranks.