No, the top should be left secured in place. The lubber hole should be sufficiently large to accept all the shrouds, plus the many running rigging lines that will eventually be sent down through it.
The lower shrouds have a sequence of installation to them. They are made up in pairs (total length a little longer than twice the distance from the upper deadeye to the masttop). The shroud is then served at the middle, sufficient to reach just below the bolsters. it is then doubled over, forming an eye, which is secured with a throat seizing, then looped over the masttop. The first pair of shrouds goes on the starboard side forward, forming the foremost (shrouds # 1 & #2) on the starboard side. Next, a duplicate pair is set up and forms the port side shrouds #'s 1 & 2. This continues, stacking up the pairs at the masttop, until all the shrouds have been made up, working your way aft; if there is an odd number of shrouds on each side, the last (single ones) are called "swifters" and are set up singly with a loop seized at the upper end.
This process is made easier if the upper masts have not yet been shipped so the pairs don't have to put manuvered around the trestletrees, if they are already in place then the throat seizings will have to be done in place after the pair has been looped around the masttop.
Good luck,
Ted