The history of the development of the 1914 doctrine needs to be kept in mind when contemplating things like a "360 day prophetic year".
During the 19th century there were literally hundreds of commentators setting forth all manner of prophetic speculations. These speculations mainly focused on when Jesus would return. The dates that William Miller set, 1843 and 1844, are good examples of this sort of speculation. Miller's followers, of course, split and evolved into various Adventist sects such as the Seventh Day Adventists and the less well known groups that C. T. Russell eventually got his date system from.
During this time, all manner of nonsensical calculations were done in an attempt to pinpoint the date of Jesus' return. Bits and pieces from various parts of the Bible were cobbled together to arrive at "prophetic time periods" and applied to various starting dates to see what ending date would come up. One of these speculations cobbled together bits from Daniel, Revelation and other places (7 times; time + times + 1/2 a time = 3 1/2 times = 1,260 days; 2 x 1,260 = 2,520; "a day for a year"; 2,520 divided by 7 times = 360 years/days per "time") to arrive at the speculative notion of this "360 day prophetic year". So the notion was pure invention based on nothing but speculation.
In view of this, it's not clear to me that it's useful to try to figure out what sort of calendar might have been used to arrive at a "360 day prophetic year". This nonsense is remembered today only because, by the luck of the draw, Adventist sects and Bible Students and Jehovah's Witnesses still exist and still promote the nonsense. Had they disappeared, like so many other groups did, these silly speculations would only be remembered in dusty 19th century books like Elliott's Horae Apocalypticae.
A related thing might be Pyramidology. Beginning in 1859, various Christian speculators wrote all manner of nonsense about how the Great Pyramid of Gizeh was intimately related to Bible history and prophecy. One commentator, Joseph Seiss, whose books influenced C. T. Russell a great deal, wrote a book in 1877 called Miracle in Stone in which he called the Great Pyramid "God's Stone Witness" ( cf. http://www.greatdreams.com/pyramid.htm ). The Bible Students parrotted this for another 50 years. In order to make their prophetic speculations come out 'correct', these guys invented what they called the "pyramid inch" which was 0.999 of a standard inch. They also invented all sorts of correspondences between measurements of various dimensions of the Great Pyramid and what they called prophecies in the Bible.
The so-called "Bible Code", which is popular today among a fairly large group of nutcases, is another case in point where pre-determined patterns are extracted from great masses of data. One can as easily extract prophecies from Moby Dick as from the Old Testament by this method.
The point here is that, just because one can find patterns in great masses of data, it doesn't mean the patterns are real. The "360 day prophetic year" is a good example.
AlanF