any HS & fans that will mount to a 775 stock bracket?

If you want the best, it's Thermalright 120 Extreme. However it may not fit in your case, so the Thermalright 90 works well too. There are many good ones, you should use google to find which one suits you best.
 


You should remove the board to mount ANY cooler. Even the stock one, gotta make sure the pins go through.