David, I have checked the Baltimore port. The only possible immigration for our Martin I find is Bremen to NY, on the Eider, arrived 4-18,1888, birth age 1828. Knowing how it is practically common to find mistakes in documents, etc, I think this may be him. A document, even headstone, is only as good as the source supplying the information. Seems especially true when dealing with Czech surnames.
When looking at current day Weinfurt's in the Plzen region, I find one living in Kanice and one in Drahkov. One in Prague and one in Prague-Kunretice.
The WEinfurt surname is of German origin from the town of Weinfurt.