When you think about it a little, remember that the crank turns exactly 2 revolutions for every 1 revolution of the cam, so in actuality installing the timing set either way is correct. Either with both marks at 12 o'clock, or with them pointed directly at each other (crank at 12 o'clock, cam at 6 o'clock). Regardless, use a straight edge/ruler that's long enough to span both the cam and the crank centerlines so that you can be sure you've got them aligned correctly. Later on, when re-installing the distributor, is when things get more specific. Turn the engine over until #1 cylinder (driver's side front) is at TDC compression stroke (both intake and exhaust valves are closed), then install the distributor so that the rotor is pointed to #1 plug wire terminal. The factory oriented things so that #1 on the cap was pointing "almost" directly at the firewall (actually sort of at the steering wheel) and the hose connection on the vacuum advance canister pointed towards the drivers side fender. If you don't care about details like that, then just plop the distributor in "however it goes", then wire the cap so that #1 wire is aligned with the rotor tip (wherever it happens to be) and connect the rest in firing order sequence, working counter-clockwise from there. Just make sure that the distributor is all the way "down" and fully engaged with the oil pump drive shaft.