This is the same height as the standard sight pin. It looks shorter because we gave it AK style ears instead of the complete loop protecting the front pin.
No bayonet is possible without turning down the barrel anyway, as the bayonet loop fits over the very small diameter end of the barrel. When the barrel is cut back to 16 or 16.5 inches, the diameter is larger, thus the bayonet would not work, just as the original front sight would not work.
This is a quick and easy paratrooper mod. No removal of the barrel from the rifle to turn the barrel end down to the original diameter under the sight.