Spines on most razors with much age to them (let alone nearly two centuries) are likely not perfect to start out with. The bevel is a straight line with the point the razor rests on a hone (if you are using tape that point isn't even on your razor) and the edge of the razor. If the grind line is rounded the angle has just been made microscopically more acute. The resting point is ever so slightly farther from the edge as it was.