Very unlikely that the way you are holding the liners down will result in a proper seal.
First, meticulously clean the liner seat in the block: absolutely spic and span, bare metal.
Next trial fit the liners and measure the liner protrusion. It needs to be relatively even from side to side and from cylinder to cylinder. In addition to shimming gaskets, you may have to swap cylinders around to get things right. Specs are in the manual.
Now coat the liner seats and bottom liner gasket face with a non-hardening sealant like hylomar. Do not use a silicone sealer. Assemble and you are ready to fit the head.
Do not rotate the engine until you do assemble the head or you may tear a liner gasket/shim'seal.