As you know, the fuel pump eccentric is simply a circle with an off center hole, bolted to the front of the cam shaft. Ideally, you would want the rotating assembly positioned so the eccentric is higher at about 12 o'clock. The only way to know that is to look. You need a bore scope type tool - like a See Snake.
The new one is usually more difficult to put in than the old one was to take out. Even the low side of the eccentric places some pressure on the pump arm. The new pumps tend to be stiffer than the one it replaces.
I agree with the above. Use an allen head bolt and washer, and taper the end. Be sure to use thread sealant - some bolt holes may extend into the crank case. Even if it's only by a tiny bit - or even a small crack - you'l get a frustrating
oil leak.