A. Your voodoo stories with cast will never end because it's very hard to weld this properly without pre and post heating to reduce HAZ (heat affect zone) cracking. Your filler selection will also determine success. Many people have successfully welded with different types of fillers depending on the area of failure. For your situation, I would see what kind of Nickel base alloy filler electrodes to use for TIG. A 50/50 Nickel rod may work for you. Between cylinders is one of the toughest areas to repair. It has to be machined extensively and hold a great amount of cylinder pressure. Outside waterjacket cracks around bolt bosses also are difficult. You will need to prep the head by cleaning, and grinding out old metal. "V" out any cracks. You may see some popping at the weld puddle while welding. This may be normal depending on the porosity of your casting. Preheat to about 200-300 degrees, weld, wrap in thermal blankets, dry sand and/or oven to cool slowly. Don't be surprised if the casting is still warm after a day or so. Like I said, everyone has success stories with cast. We all have failures too. You just don't hear too much about the failures
Good luck and let me know your findings.