I’m not sure there is a way after it is installed to reallocate missing drive space. How did you go about ‘restoring’? The recommended method to upgrade to ssd is with a ‘fresh install’ of hassos 3.5rc… then you restore your data from a snapshot file (which should be taken before the upgrade).
Since some folks have had issues with snapshot restores, I would also recommend first attempting to restore a full snapshot on your existing system to make sure it works before attempting to upgrade to an ssd.