I've been considering trying some cast iron repair using nickel alloy wire in my MIG welding machine. The old tried and true method of "pre-heat- - - -weld- - - -post heat- - - -peen" and then bury the part in sand to slow cool overnight seems to be the best way to deal with the nasty habit of cast iron to crack right beside a repair. I'm thinking of skip welding 1/2" beads with a MIG and peening after a pretty good preheat to stress relieve and doing a slow cool-down. A long crack like the one in the picture might take a week or more to get a full repair. Once the crack is welded, a coat of Marine-Tex and pressing a piece of 40 grit sandpaper over the fill as it's curing to put the textured appearance back into place will hide the repair and seal off any pinhole leaks.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!