I found a rare engine block for dirt cheap because it has what the seller calls extensive freeze damage in the lifter valley area to the water jackets. The cracks can only be seen with Magnaflux, not to the eye. It would save me over $2000.00 dollars if it is repairable. Do any of you have experience and advice on taking on a task like this? Which process would be best used and what filler metal is best?

Thanks in advance!
Bob