The maximum the block can be bored will be as stated above, it will mainly be dictated by the results of the sonic check. Personal experience has found the CJ blocks being less conducive to boring over 0.030" as opposed to the standard run of the mill passenger car blocks.
Turning the crank though can be as much as 0.050" as the bearings are available. There will be no wear issues with a crankshaft turned this far but care must be taken in that the
oil holes for the journals move closer towards the journals edge when starting to turn crankshafts more than the generally accepted amounts. This can usually be spotted before actually turning the crank if being looked for. The other thing to watch out for is that shop doing the crankshaft grinding puts the correct radius at the journals edge in order to maintain crankshaft integrity in this area.