Yes it is a grade of babbitt that could be used for the Model A engine. It is not the Ford blend, but will work.
http://nfmetals.com/babbitt-metal/
https://www.fordgarage.com/pages/babbittgrades.htm
That being said, pouring babbitt properly is a complicated process based on known science. It is not something to be done sucessfully by an inexperienced person. In fact, there are video showing current engine shops doing babbitt improperly. Babbitt poured improperly will fail in time long before it wears out.
The babbitt you have is likely worth more then the cost of the lead needed to replace weight in the sailboat. There are people that would be happy to pay for it. Oh, shipping is best by USPS one rate boxes.