Hi Vyedma.
Here are the Lillian orbs that I use, for horary and anything else. As the horary branch of astrology is usually more based upon traditional techniques than other branches today, such as a full scheme of dignities and debilities etc. then I imagine that these traditional orbs would be the most appropriate to use, as used by Lilly.
Sun - 15 (degrees)
Moon - 12
Mercury - 7
Venus - 7
Mars - 7
Jupiter - 9
Saturn - 9
So, for an aspect between the Sun and the Moon, the maximum orb allowance would be 13 and a half degrees, because you add together the 15 and 12 degree orb value of both and then halve that value which give the maximum orb allowance.
For Venus and Mars, 7 degrees.
Jupiter and Mercury, 8 degrees, and so on.
http://www.skyscript.co.uk/aspectorbs.html