DinoBru Here are the pics of my B20B head.
This is the area near the thermostat housing. Note there isn't any hole for a sender, but there appears to be a flat which could carefully be drilled.
This is the RH side of the head, where there's a cover plate fitted to B20A and B20B engines (carb).
This is the casting number.
This is the front of the head, where there's a pair of welsh plugs. The bolt on the LH of pic is for an accessory bracket.