340 is gutted

well, if there is no hone marks, and it's .030, it may have been an average rebuild. Poor maintenance is damaging no matter a factory or rebuilt. Dont bother with .035..Go to .040 over. there is no problem with that, even with a longer stroke crank. The weld you see, is most likely a balance job where they welded in the Mallory metal. Press fit isnt enough on a striong engine. Teh cranks move around too much. So you tack the plugs in..