1968 340 block, parts, 727

Sleeve it??
it works on Hemi's, it works on 440's and 383's and 318's why not a 340?
while you are at it...grind the valves on those J's to the same size as the X's

must be something else in your future....all that is less expensive that pickin up a crate or taking a chance on someone else's problems...but its your call