Is there a reason for the risk? Welding the block sounds "iffy", especially in light of the lack of preheating and anealing. If you did get it welded and built an engine around this block, what are you risking in the event that it didnt work? I would hate to see someone put a bunch of $$ and time in a neat flat motor and have it fall down because of the patch...... if you are building it with used, stock stuff, then the risk is much less and might warrant the roll of the dice..... good luck on whatever you decide.