Trying to assign the most signs of linear A to their linear B counterparts, one sooner or later stumbles into really problematic questions. After the assignment of the simpler signs (that were already done more than a decade ago, see the works of Jean-Pierre Olivier and Louis Godart), a handful of unique ones remain, that do not show obvious similarity to one or more of the (yet unassigned) linear B signs. Well, for at least for the first sight...
The LinA sign I will treat here bears the label of *306 - it is so high because scholars initially believed it to be a logogram. I would not say it is not used as a logogram on some places (e.g. KH6, where it likely stands for some kind of animal), but in most of its occurrances, it is a phonetic sign. Examples include the tablets HT6, HT119 and HT122 (*306-TU), HT115 (*306-TU-JA), HT122 (?-*306-KI-TA2)and HTwc3017 (DI-*306). But this sign is not particularly frequent, and these examples are - unfortunately - insufficient to guess at the phonetic value directly. All we can say is that the syllabe it represented was prone to stand word-initially.
If we believe (and this is clearly a hypothesis) that the use of this sign continued into the mycaenean era, we may attempt to search for a parallel in Linear B. As I stated before, sign LinA *306 belongs to the group of "animal-signs", i.e. those depicting various (domesticated) animals. Most of them have heavily simplified graphical structure, and are often used as logograms as well. Such examples of somewhat similar signs include the LinAB *23 sign (with the value 'MU'), that is sometimes used as a logogram for "cattle" or the LinAB *21 signs (phonetic value: QI), depicting (albeit simplified) the head of a sheep (and being a logogram for the latter). Fortunately, this group of signs is very limited in its numbers and their structure is very characteristic: with 1 line inserted below the main bulk ("head") as a "neck" and with an occasional addition of a "skirt" (an additinal vertical line) or "pants" (2 horizontal lines) to indicate the gender of animals.
If we look at the sign *306, we can guess the following: the animal it stood for is female (as *306 always bears "skirt"), and it has 2 prominent appendages on its head (horns or long ears), in addition to a large, bulky head. Now, if we go to the linear B signs, we may attempt to search for a sign with similar characters. However, one shall quickly find that the signs for "sheep" (LinAB *21), "goat" (LinAB *22), "horse" (LinB *105, LinA *336), "cattle" (LinAB *23) or "pigs" (LinAB *85) were already assigned to linear A signs, with great certainty. So the job of finding a counterpart is not that easy. Fortunately, we also know that LinA *306 also had a phonetic value used reasonably regularly. So we may search among the purely phonetic signs as well. There we may encounter LinB *42, that has a similar graphical structure to LinA *306. It has a skirt-like triangular lower part, with a line-like head, containing 2 appendages behind. So it is not beyond reason that linB *42 originally represented some kind of animal. Unfortunately, I cannot cite even a single unambiguous example, where linB *42 would have been used as a logogram. This leaves us a good guess at what kind of animal it may depict. My guess would go at "mule" or "donkey", (the latter maybe because the mycaenean greek word "Onos" = donkey rhymes well with the phonetic value of LinB *42 = WO ) but that is purely hypothetic.
As I mentioned before, the sign LinB*42 has the phonetic value 'WO' in linear B documents. But could a sign beginning with 'W' stand so frequently word-initially in Linear A? Without dismissing the hypothesis that LinA *306 is indeed 'WO' with no proposed phonetic change between LinA and LinB, let us look at other examples of 'W'-signs! A striking discovery is that both WA and WI (the only two such signs attested with certainty) are unexpectedly prone to stand word-initially. So, after all, words beginning with "WO-" in Minoan might not be misreadings at all.