  The low-energy spectrum of $N$-boson clusters with pairwise zero-range
interactions is believed to be governed by a three-body parameter. We study the
ground state of $N$-boson clusters with infinite two-body $s$-wave scattering
length by performing {\em{ab initio}} Monte Carlo simulations. To prevent
Thomas collapse, different finite-range three-body regulators are used. The
energy and structural properties for the three-body Hamiltonian with two-body
zero-range interactions and three-body regulator are in much better agreement
with the "ideal zero-range Efimov theory" results than those for Hamiltonian
with two-body finite-range interactions. For larger clusters we find that the
ground state energy and structural properties of the Hamiltonian with two-body
zero-range interactions and finite-range three-body regulators are not
universally determined by the three-body parameter, i.e., dependences on the
specific form of the three-body regulator are observed. For comparison, we
consider Hamiltonian with two-body van der Waals interactions and no three-body
regulator. For the interactions considered, the ground state energy of the
$N$-body clusters is---if scaled by the three-body ground state energy---fairly
universal, i.e., the dependence on the short-range details of the two-body van
der Waals potentials is small. Our results are compared with the literature.
