Had a look at that Massachusettes broadside catalogue on Google Books.
The Fleets were printing at the Heart and Crown from 1731 to 1776 and then they move to the Bible and Heart, but the Bible and Heart was a printing house in 1738 (see item 693) 'Printed and sold at the Bible and Heart in Cornhill, Boston.' Not many printed ballads appear to have survived from the period, though it mentions Fleet purchasing in 1748 a stock of captured Papal Bills the backs of which he used to print ballads on.