Don not stain the cutting board portion of your counter top at all. For the rest of the counter top you can put any stain you want on it. Finish is with Watco Butcher Block oil. Its a mix of Mineral Oil, Tung Oil and lindseed and leaves a Varniq finish that is safe for indirect food contact. There are a few others on the market like Durakryl-102, Emmitts Elixr and The Good Stuff. They are all safe for indirect food contact. Safe to cut on too just not recommended for heavy chopping. For more info see the link below. Here is a link that might be useful: The Butcher Block Top

Recommendations? Don't do it. If you don't sand out all of the existing scratches very thoroughly before staining, then more pigment will lodge inextricably in the remaining scratches. This will look bad. If you manage to refinish the counter successfully and then start using it as a cutting board, you will soon cut through the stained wood in places. This will also look bad. Even setting food safety aside, a cutting board is just the wrong place for stain.

What type of wood? Different woods take different stains...open pore like oak =can take a pigmented stain, sometimes tight grains like maple do better with a gel stain. Sand all surfaces to remove any burnished areas and to get all grain evenly "scratched". Here's a teak butcher block I made a while ago: Is this the color family you're looking for?

John Boos - I got a 27" deep piece of blended maple, 5 feet long and I think it cost about $200. We have ikea cabinets installed against the wall and its insane how much larger it feels than a 25" top. The countertop rule of thumb is the counter should overhang all sides of the cabinet. You should add a minimum of 3" to the depth and 3" to the width. If you're adding wainscot or some other form of panels on the back and sides, those would add a little bit more. 27" would be about as small as I would go in depth - but you could also choose to go wider. I've seen some pretty cute tops that overhang more and have a bowl cut out for scraping cut veg into a bowl. Just watch out that you can reach the entire inside of your drawers with the overhang that you've chosen. For length, you'd need the length to be 4 feet and you'd cut it to the exact size. Sand the cut edge to match the manufactured edge. Again, you can go a little longer. For instance have an overhang of 4 inches on both sides and mount hanging rails. For knife use, get one finished in mystery oil or completely unfinished.