The Reformed Presbyterian Church in Manassas, VA is the place you should check out, Reformed Presbyterian Church Home Page. It is solidly Reformed. It is also the home church of the Christian Observer, the oldest Christian publication in America.
I have visited this church and was warmly received.
When we lived in Virginia, we attended Trinity Presbyterian Church in Charlottesville and loved it. It’s not in Manassas, but when living in Lynchburg we thought it was worth the hour’s drive to get there.