When building the R1 I had an engine which had been totally emptied of coolant for some time. It took me several attempts to fill it. You need to employ some common sense to remove airlocks, the best thing I can recommend is to loosen all the hose clamps, bleed screws etc..., and then fill the system slowly and do up each hose clamp as it starts to leak, making sure that it is no longer leaking any air, only coolant.
As mentioned already, even if your temp sender is duff, it won't cause overheating. That will only be caused by a) lack of coolant somewhere, b) water-pump not pumping enough volume of coolant, c) radiator fan not coming on, d) thermostat not opening, e) engine putting out too much heat due to running lean or being mis-timed.
How do you know that it's currently overheating? You know that the system SHOULD be pressurised when up to temperature right?