It certainly does matter where the slot is oriented. It matters so that the distributor will fall in the right place and have enough room for the vacuum advance can to move without hitting anything. The factory service manual details the installation, so it surely does matter.
Also, it appears you may have it off by one tooth. I THINK it might need to rotate ONE tooth clockwise. Technically. the slot is supposed to point to the first intake manifold bolt hole on the driver's side cylinder head. That's what the manual says. Yours appears to be pointing a tad counter clockwise of that, although it is hard to tell.
Yes, technically, you CAN point that slot any direction you want and it will run fine, but, there is only one totally correct way. That is the way I prefer and I would not advise anyone to do it otherwise. JMHO.
