The first broadcast, rather early in the month on Wednesday, October 15, 2014, from 8:30-9:00 PM (Eastern/Pacific), will be edited to fit into the half-hour timeslot (because networks show more commercials now than they did back in 1966).
The second outing of the classic Halloween television special on Thursday, October 30, 2014, from 8:00 - 9:00 PM (Eastern/Pacific), is not only more timely, but will be unedited and accompanied by You're Not Elected, Charlie Brown, as in previous years.
So if you want to see the whole pumpkin, tune in October 30 - although of course, ABC would be even happier if you tuned in both times!
(Note: initially ABC only announced the Oct 15 broadcast; the Oct 30 broadcast wasn't announced until several days later. So this post has been revised accordingly.)