To answer the question one must first define what is meant by heaven. If by heaven is meant a physical (necessarily so because of the resurrection of the body) and spiritual location somewhere other than this universe where all the saints will go to worship God eternally, then the answer is “no.” Heaven, in this sense, is a revealed doctrine and cannot be known by reason alone.
However, if by heaven one means that our end lies is the one Uncreated Creator, then I would venture to say, “yes.”
We can know, by reason alone, that there can only be one perfect end of man common to all men who possess a human nature—since the end of a thing flows directly from its nature. Introspection or self-reflection quickly reveals that we have a desire to know the ultimate truth, hence our inborn desire to know things (in search for that ultimate truth), and to possess the ultimate good, hence our inclination to that which is good and our aversion to that which is not. In addition, we can conceive of such a truth and such a goodness existing, whether or not we conceptually know it in its fullness, and this lends itself to the fact that such a truth and goodness exist.
We see that creation is good—It contributes to our perfection as human beings and gives us what we need to journey on in that search of perfect truth and goodness. This being the case, however, one can know that this ultimate truth and goodness cannot be found in any created thing since every created thing lacks the goodness that created it, for an effect cannot be greater than its cause.
Ironically, it is a dogma of faith (infallible) that the existence of God can be known by reason alone (This is stated in the First Vatican Council’s document, Dei Filius, 2). This, however, is for good reasons that space will not allow us to develop in the present post. That being said, if it is true that God exists, logically we can deduce that, properly speaking, He (“It” without revelation?) is the only Uncreated Creator. Being, then, the source of creation, and therefore the source of all its goodness, we can see that God alone is the ultimate good that we seek to possess in its fullness. The same holds true for the ultimate truth that we seek via the same line of reasoning.
Therefore, yes, we can conclude that we do not need revelation to know that man’s last end is perfect and unmediated union with God, the ultimate Good and Truth.