Take measurements of your most comfortable flat bar bike and try to duplicate them on the drop bar bike. Use the top of the drop bars as if it was a flat bar. There should be no reason why you can't find the same position.
Drop bars come in many shapes and sizes. I use a short reach shallow drop bar on my road bike. My back isn't as flexible as it once was.
And yes, there are offensive linemen on road bikes, but they do trim down a bit. My friend was offensive team captain in college and shrunk down to 265 pounds to ride road bikes and started racing at the velodrome and did well.
Another offensive tackle (college) rode with our club for years and varied between 265 and 280 pounds. Quite strong on the flats, he raced crits as a cat 3.