My SAR-1 has a side rail on which red dot sights and scopes can be locked using a lever. They are very secure once mounted.
The side rail may be what you are calling the "block-lever."
Otherwise, I don't know what the Squeeze Block, block-lever, and VEPR mounts are. VEPR is a model of AK and I don't think there is an optic mount per se called the VEPR.