HEGO sensor is most liklely an NTK and these are longer.
It is in the right place, or should say best place as up to temp quicker here they do not work at low temps, so will mix go open.
Turbo is a mix of 2 + 4wd TB03 is start of model number not T803.
Looks like 4wd turbine and 2wd compressor.
Boss is standard thread for HEGO so just buy a nut, same thread, drill a hole in exhaust and weld in, wherever you want it.
tabetha