Clean off the varnish from the top side of the tongue of salvaged boards?

Q: We salvaged some 7/8 quarter sawn, hard pine flooring. We would like to know how to clean off the varnish from the top side of the tongue edge of the boards? We have a scraper, however we are wondering if there is any easier way, as it seems that the varnish has turned to cement.

A: I would think if you have a router and router table with a straight bit, you could set it up so it will cut up to but not remove any of the tongue. Once it is set up, you can just run the boards through fairly quickly.