Back to basics...yes, I agree your 180* out...or, is it only 90*?
Afraid this will be a little long winded.
Pull all the plugs, to make it easier to turn the engine over, by hand. Then pull the distributor. Watching both your timing marks, and watching (through the distributor hole) the two lifters for #1 cylinder, rotate the engine.
To get #1 cylinder at TDC compression stroke, the timing mark will go to 0, and the two lifters for #1 will be fully down. Easy to check when you get there, by moving the engine back, and forth, watching the lifters. If both move, one at a time (just like mentioned), it's on EXHAUST stroke. If neither move, it's on compression stroke...where you want it.
Keep in mind, #1 comes to top twice, once on compression, once on exhaust strokes.
Now rotate the engine 'backwards', until timing mark is off the timing plate. That's to get gear slack out. Then, in correct rotation, turn until timing mark lines up with 12* btdc, or where ever you want the timing at.
Then, put the plugs back in. Then, to the distributor. Quit worrying about where the rotor is pointing, and all that nonsense. Your going to put it where you want!
Normally, if installed right, the slot at the top of the drive gear, would be in line with the cam...front to rear. It can easily be turned, by lifting the gear, turning it, and drop it back in.
Pull the distributor cap, if you haven't yet. Consider, while dropping the distributor in, where the advance 'can' will be, so the distributor has swing clearance, to adjust timing. With the distributor in place, take note where the rotor is pointing, AND where the locating tab is, for the cap location. Cap should go on only one way.
Then, look at the cap, for the plug wire location on the cap, that the rotor is pointing to. That's where #1 plug wire needs to be! If it is not...pull all the plug wires off the cap, get #1 in the right place, and go from there for the rest of the wires, going in firing order.
Once that's done, cap back off, and look at the points (or, if electronic, at the fingers), and just rotate the distributor, until the points are at the point of opening (or, the finger is just coming up to #1 finger, if electronic).
You also want the rotor 'finger', to be located where it is just coming to the #1 contact inside the cap...not directly at the contact. It fires off, when it gets at that point.
Tighten down the distributor clamp, put the cap on, and fire off the engine...