My early XJ, 88, has a whole lot more possiblities than 180 out, can install the distributor in a bunch of wrong positions.
Put a compression gauge on the 1 plug and turn it over until, you get pressure. Line up the timing "0" mark on the balancer (easier if you chalk a mark on the front of the balancer)( always last turn to "O" to the right to take the slack out of the chain). Turn the oil pump slot until it lines up and install with the distributor rotor pointing towards the "1" mark on the cap (close or slightly after). The distributor kinds of twists, some as it goes in, sometimes hard to get the oil pump drive to line up in the slot. With a long screw driver you can turn the oil pump drive (slot) to close to where you want to be. A little trial and error, will get the shaft and the pump and the "1" mark lined up (near enough). With the 1 cylinder at the top of the compression stroke.