CONGRATS MARTY!!!!
Next time you need to fill up the cooling system on an LS, keep the top hose loose and fill from it, it will ensure you get the entire block full with hardly any air left in the system. It also bypasses the thermostat so filling is much quicker. Basically the same idea as pulling the thermostat housing from a SBC/BBC and filling the cooling system from the thermostat hole in the intake. Makes a huge difference in the end.
Get some smiles per mile son, you deserve it!!