I've also used the lock-n-stitch pins with good results, on the decks of a couple of factory SOHC heads.  Should be a good solution on the deck of the block.  However, I'd look carefully at the blocks to make sure they haven't been sleeved in the bores on either side of the crack.  A lot of folks have tried to sleeve adjacent bores and run into problems after the repair, when the block cracks between the sleeves after a few heat cycles.  If you find the sleeves, I don't know of a good solution for a permanent repair to the cracked area, but I think I would try a bunch of the lock-n-stitch pins, spread out across the area between the bores and extended into some of the wider space between the bores.  
Also, once you finish with the lock-n-stitch repair, you have to machine the surface flat, so make sure you leave a little bit of the pins exposed above the deck.  Good luck with the repair, Alan.